feat: copy the output panel to the system clipboard (#11)

New app-level `copy` / `copy all` / `copy last` command (ADR-0041).
Delivery is OSC 52 *and* a best-effort native write (arboard), always
both — OSC 52 acceptance is undetectable, so a true fallback can't be
built. Payload is the panel's plain text exactly as rendered (tags,
✓/✗, box-drawing), drift-locked to render_output_line. arboard added
--no-default-features (X11-only; OSC 52 covers Wayland).

Amends ADR-0003's command registry; requirements V6.

docs/adr/README.md

@@ -8,7 +8,7 @@ This directory contains the project's ADRs, recorded per
 - [ADR-0000 — Record architecture decisions](0000-record-architecture-decisions.md)
 - [ADR-0001 — Language and TUI framework](0001-language-and-tui-framework.md)
 - [ADR-0002 — Database engine](0002-database-engine.md)
-- [ADR-0003 — Input modes and command dispatch](0003-input-modes-and-command-dispatch.md) — the persistent `Simple`/`Advanced` mode and the `:` one-shot escape. The **startup mode is no longer always `simple`**: it is restored from the project's stored mode and overridable with `--mode` (see **ADR-0015 Amendment 1**, issue #14)
+- [ADR-0003 — Input modes and command dispatch](0003-input-modes-and-command-dispatch.md) — the persistent `Simple`/`Advanced` mode and the `:` one-shot escape. The **startup mode is no longer always `simple`**: it is restored from the project's stored mode and overridable with `--mode` (see **ADR-0015 Amendment 1**, issue #14). The app-command registry gains **`copy`** (ADR-0041, issue #11)
 - [ADR-0004 — Project file format](0004-project-file-format.md)
 - [ADR-0005 — Column type vocabulary](0005-column-type-vocabulary.md)
 - [ADR-0006 — Undo snapshots and replay log](0006-undo-snapshots-and-replay-log.md) — **Accepted**. The **replay/journal half** (U3/U4) shipped via ADR-0034; the **undo/snapshot half** (U1/U2) is settled by **Amendment 1 (2026-05-24)** and **implemented 2026-05-24** (plan: `docs/plans/20260524-adr-0006-undo-snapshots.md`; ring in `src/undo.rs`, worker hook in `src/db.rs`). Amendment 1 **supersedes the original "snapshots only before destructive operations" model**: a snapshot is taken before **every** data/schema mutation (DSL + SQL) for familiar single-step (Ctrl-Z) undo — so the confirmation collapses to *naming the one command being undone* (no db-diff). Snapshot is a **hybrid whole-project copy** — database via the online backup API **plus** `project.yaml`/`data/*.csv` as files — reconciling this ADR with ADR-0015's "text is authoritative, db is derived"; undo restores all three directly. Staged before the mutation's transaction, finalised after the db commit (preserves ADR-0015 §6 commit-db-last); rolled-back ops leave no snapshot. **Persisted** ring under `.snapshots/`, **N = 50** (raised from 10), git-ignored + export-excluded + temp-cleanup-aware. `redo` supported, **redo stack discarded on new work**. **Batch ops record one undo step** (`replay` + future batch via a Begin/EndBatch worker primitive); **`import` is outside undo** (it switches projects per ADR-0015 §11, leaving the current project untouched). A **`--no-undo` CLI flag** disables snapshotting (hardware escape hatch). Adds the `backup` feature to `rusqlite`
@@ -46,3 +46,4 @@ This directory contains the project's ADRs, recorded per
 - [ADR-0038 — The DSL → SQL teaching echo](0038-dsl-to-sql-teaching-echo.md) — **Accepted** (design agreed 2026-05-27; **fully implemented + verified** — every catalogue row in §7 Buckets A + B and the §6 category-3 prose round-trips per line through the advanced walker per §1, and the §4 de-emphasised styled-runs polish is wired: handoff-46 `04c8e42` shipped the channel + create-table slice, handoff-47 `90479cb` the full Bucket A expansion + a skeleton contract-gap fix (dropped per-column `DEFAULT`/`CHECK`), `275c726` the Bucket B resolved-name + multi-statement renderers (auto- and user-named `add index`, positional `drop index`, `add`/`drop relationship` in both selector forms, `drop column --cascade`, `add relationship --create-fk`), `e6ad1ae` the last category-3 line — the `change column --dont-convert` *caveat* (shortid + transform notes were already surfaced via pre-existing `client_side.*` keys), and `2aab457` the §4 styled-runs polish: a new `OutputKind::TeachingEcho` custom rendering branch (dimmed `Executing SQL:` prefix + the SQL re-lexed in advanced mode for token-class colouring, same as the input echo) plus a new `OutputStyleClass::Hint` for every cat-3 prose line — caveat *and* the existing illuminating notes, user-confirmed broader scope), **realises ADR-0030 §10** (the teaching bridge) — the Phase-5 echo **ADR-0035 §12 forward-referenced** — building on **ADR-0037** (the `SubmissionMode` gate) and **ADR-0035 Amendment 2** (standard-first dialect + `ALTER COLUMN` gap-fill). When a **DSL-form** command runs in advanced/one-shot mode, the worker emits the equivalent SQL beneath `[ok]` as a de-emphasised styled `OutputLine` (ADR-0028); the App renders it. **Defining invariant — the copy-paste contract:** every echoed line is *runnable advanced-mode SQL* (round-trip-tested: parse the echo → same-effect command; a planned "copy the echo" affordance depends on it). **Type vocabulary = the playground's own keywords** (`serial`/`shortid`/…, accepted by `from_sql_name`, decision (a)); **statement shape = the standard-first dialect** (Am2). **DML uses substituted literals, not `?`** (per-type `Value → SQL-literal`, round-trip-safe; `blob` moot — no literal syntax exists; auto-gen columns omitted to match `do_insert` + X4). **Firing reality — a DDL + `show data` feature:** in advanced mode `insert`/`update`/`delete … where` are SQL-first (`Sql*` = already SQL = nothing to echo per §10); only DSL-*only* spellings echo (DDL + `show data` + the `delete`/`update … --all-rows` fall-throughs — the latter via **ADR-0033 Amendment 4**, a bug-fix folded in here that reverses Amendment 3's `update … --all-rows` misparse). **Three-category framework** for "what happens beyond the literal SQL": **(1) engine-implementation-hiding** (the rebuild, rowid PK, non-PK `serial` MAX+1) — *never surfaced*; **(2) decomposable into advanced SQL** (`drop column --cascade`, `--create-fk` relationship) — *shown as the runnable multi-line sequence, one statement per line*; **(3) playground type-behaviour with no SQL-expressible form** (`shortid` generation — no `shortid()`; type-conversion transforms — no `USING`) — *de-emphasised prose expansion from the worker's `client_side.*` notes*. Carries the **full catalogue** (Buckets A single-statement / B resolved-name + multi-line / C no-echo) mapping every DSL-form command to its echo. OOS: reverse SQL→DSL echo (§13 OOS-5), app commands / `show table` / `explain` / `replay`, a `blob` literal, the column-level UNIQUE/CHECK drop residual (Bucket C until Am2's gap closes), and surfacing any category-1 engine internal
 - [ADR-0039 — EXPLAIN over advanced-mode SQL queries](0039-explain-over-advanced-sql.md) — **Accepted** (2026-05-27), **implemented 2026-05-30 (issue #7)**, **supersedes ADR-0030 §13 OOS-2**. Lets `explain` wrap the advanced SQL commands (`Select`/`SqlInsert`/`SqlUpdate`/`SqlDelete`, plus `with`/CTE which builds a `Select`) in addition to the DSL `ShowData`/`Update`/`Delete` it already covers (ADR-0028), running `EXPLAIN QUERY PLAN` over the validated SQL text through the existing ADR-0028 span-styled plan tree (advanced mode only; DSL `explain` unchanged in both modes). Implemented via a second `Advanced` `explain` CommandNode (`EXPLAIN_SQL`) registered under the shared `explain` entry word — reusing the established `insert`/`update`/`delete` shared-word dispatch (`decide`: SQL-first / DSL-fallback), so `explain show data …` and DSL-only `--all-rows` still reach the DSL node; rejected a `DynamicSubgrammar` mode-gate (its resolution cache key omits `mode`). `build_explain_sql` slices the inner SQL off the source (excludes `explain`) and reuses the existing SQL builders; `do_explain_plan` runs the carried text verbatim, no params. Advanced `explain update`/`delete` now route through SQL (identical plan, full SQL syntax); DSL-explain tests pinned to simple mode. Reframed OOS-2 as a *deferred* exclusion (per ADR-0000's out-of-scope discipline), not a rejection. OOS (deferred): EXPLAIN of DDL (no query plan exists)
 - [ADR-0040 — A per-command completion marker (✓/✗) replaces the `[ok]` summary line](0040-completion-marker-replaces-ok-summary.md) — **Accepted 2026-05-30 (issue #9)**, amends ADR-0014 / ADR-0028 / ADR-0019 output conventions, builds on ADR-0037's mode-tagged echo. An audit of the whole command surface found the `[ok] <verb> <subject>` summary line duplicates the echo line above it (verb+subject) everywhere; its only unique contribution is the success-vs-error signal (and `explain select` even rendered `[ok] explain` with an empty subject post-ADR-0039). Decision: drop the `[ok]` line and the symmetric `"…" failed:` prefix; the echo line gains a trailing inline **✓** (green, success) / **✗** (red, failure) — `running:` becomes a pending state that resolves to `<input> ✓/✗` on completion (status set via the existing `rfind(Echo)` lookup). Content (row counts, structure, data, plan tree, teaching echo) unchanged. Scoped to the DSL/data/SQL family that has the redundant echo+`[ok]` pair; app-command `[ok]` lines (`rebuild`/`export`/`now editing`) are payload-bearing, have no echo to mark, and stay as-is. `ok.summary` retired; `dsl.failed` reduced to the rendered reason. Broad but mechanical snapshot churn. OOS: app-command `[ok]` lines, the `[WRN]` validity indicator, and the tag colours (issue #10)
+- [ADR-0041 — Copy the output panel to the system clipboard](0041-copy-output-to-clipboard.md) — **Accepted 2026-06-02 (issue #11)**, amends ADR-0003's app-command registry (adds **`copy`** / `copy all` / `copy last`). The friction it removes: filing a bug report meant terminal-selecting the output panel and fighting wrapping/borders. New **app-level command** (sigil-free, both modes): `copy` / `copy all` copy the whole panel; `copy last` copies from the most recent echo line to the end. **Mechanism — OSC 52 *and* native (`arboard`), always both**, because OSC 52 acceptance is undetectable (no terminal ack), so a true "fall back when unsupported" can't be built: emit the OSC 52 escape (no new dep — `base64`+`crossterm`; works over SSH; tmux-passthrough-wrapped via `$TMUX`), then a best-effort native write whose failure is ignored (headless host — OSC 52 carried it); the two carry identical content. **Format — plain text verbatim as rendered** (tags, `✓`/`✗`, box-drawing) joined by `\n`, without viewport padding/wrapping; a drift-lock test pins `OutputLine::plain_text` to `render_output_line`. `arboard` added **`--no-default-features`** (drops the `image` crate; X11-only on Linux — `wayland-data-control` deliberately omitted as it ~doubles the dep tree and OSC 52 covers native-Wayland). Security: write-only, scans clean for arboard's tree (cargo audit / osv-scanner / grype), 1Password-maintained, minimal surface. OOS: Markdown export, selection/range, a keybinding, OSC 52 read, `screen` passthrough