feat: ADR-0035 4a — SQL CREATE TABLE command, worker, and exit gate

Command + builder + worker for advanced-mode SQL CREATE TABLE
(sub-phase 4a), executed structurally through do_create_table:

- Command::SqlCreateTable + build_sql_create_table (ddl.rs): aliases via
  from_sql_name (incl. double precision), column- and table-level
  PRIMARY KEY, redundant-flag de-dup off a sole PK, IF NOT EXISTS.
  Advanced REGISTRY entry on the shared `create` word (SQL-first, DSL
  fallback); no-PK tables allowed (user-confirmed).
- Worker (db.rs): Request::SqlCreateTable + CreateOutcome + snapshot_then
  (one undo step); IF NOT EXISTS no-op (no snapshot, but journalled, like
  read-only commands). do_create_table inline-PK rule aligned with the
  rebuild generator schema_to_ddl — no round-trip DDL drift; serial
  autoincrement is independent of inline-PK (verified by round-trip
  tests).
- Runtime/App: dispatch + CommandOutcome::SchemaSkipped +
  AppEvent::DslCreateSkipped (structure + "already exists — skipped"
  note). Friendly catalog keys added (engine-neutral).

DEFAULT/CHECK/table-level UNIQUE are absent from the 4a grammar (parse
error with usage skeleton; friendly message + support land in the 4a.2
constraint slice) — user-confirmed.

Tests: type resolver, grammar shape, builder (incl. the PK
detection bug they caught), and tests/sql_create_table.rs (worker
round-trip, serial autoincrement first/non-first across rebuild, IF NOT
EXISTS no-op + journalling, no-PK table, one undo step) + a replay-as-
write test. 1739 pass / 0 fail / 1 ignored; clippy clean.

Exit gate: ADR-0035 Proposed -> Accepted (validated end-to-end by 4a);
README + requirements.md Q1 updated.

docs/plans/20260524-adr-0035-sql-ddl-4a.md

@@ -292,15 +292,22 @@ the ADR flags).
    Single-word aliases + an optional discarded `(len[,len])` cover the
    rest. Delivers the ADR §3 item without bending it.
 
-4. **`serial` PK inline emission (implementer call, step 3/worker).**
-   `do_create_table` today inlines `PRIMARY KEY` (the rowid-alias that
-   makes `serial` autoincrement) **only when the table has one column**.
-   SQL mode allows `CREATE TABLE t (id serial primary key, name text)` —
-   a `serial` sole-PK in a multi-column table — which would otherwise
-   get a table-level PK and **lose autoincrement**. Step 3 extends the
-   inline condition to "sole-PK column whose type is `serial` → inline
-   `PRIMARY KEY` on that column," leaving the simple-mode paths
-   (single-column, or compound) unchanged. Covered by a worker test.
+4. **`do_create_table` inline-PK rule aligned with `schema_to_ddl`
+   (implementer call, step 3/worker; corrected by the `/runda` probe).**
+   *Original premise (wrong):* a `serial` sole-PK in a multi-column SQL
+   table needs an inline `PRIMARY KEY` (rowid-alias) or it loses
+   autoincrement. **A round-trip probe disproved this:** after a rebuild
+   the table gets a *table-level* PK (`schema_to_ddl` only inlines a
+   first-column PK), yet `serial` still autoincremented — the insert
+   path computes the next value itself, independent of rowid-alias.
+   *Actual fix:* `do_create_table` now uses the **same inline rule as
+   `schema_to_ddl`** — inline only a single PK that is the **first
+   column** — so a freshly-created table and its rebuilt form have
+   identical DDL (no round-trip drift, the real latent issue a
+   multi-column SQL create would have exposed). Simple-mode paths
+   (always single-column create + `add column`) are unchanged. Covered
+   by two round-trip tests (serial PK as first **and** non-first
+   column survive a rebuild).
 
 5. **Redundant PK constraints (implementer call).** SQL mode is
    **lenient** like real engines: `id int primary key not null` /
@@ -311,6 +318,24 @@ the ADR flags).
    mode deliberately, matching the advanced-mode "trust the user like
    SQL" posture, ADR-0035 §7.)
 
+6. **Deferred constraints surface as a parse error (user-confirmed
+   2026-05-25).** `DEFAULT` / `CHECK` / table-level `UNIQUE` are absent
+   from the 4a grammar, so typing them is an ordinary parse error — the
+   ADR-0021 usage skeleton lists the supported `CREATE TABLE` form,
+   implicitly communicating what is not yet available. A bespoke
+   "not yet supported" message needs the deferred expression-parsing
+   work and so lands with 4a.2, when those shapes are added.
+
+7. **No-PK tables allowed in advanced mode (user-confirmed
+   2026-05-25).** `create table t (id int)` with no primary key is
+   accepted (standard SQL; the §7 trust posture), unlike simple mode
+   which requires/defaults a PK. Pinned by a worker test.
+
+8. **No-op skip is journalled (`/runda` fix).** A successful
+   `CREATE TABLE IF NOT EXISTS` no-op appends its line to `history.log`
+   like other read-only/no-op commands (`show table`) — the complete
+   journal (ADR-0034) — while taking no undo snapshot.
+
 ## 7. Devil's Advocate review of this plan
 
 - **Does it reuse rather than fork execution?** Yes — `do_create_table`