feat(help): distinct help for advanced-mode SQL forms; split list by mode (#36)

The six advanced SQL DML/query forms (SELECT, WITH, SQL_INSERT, SQL_UPDATE,
SQL_DELETE, EXPLAIN_SQL) carried help_id: None, so `help select`/`help with`
resolved to nothing and `help insert` showed only the simple form. Give each
its own distinct help_id (data.select, data.sql_insert, …) with a hand-curated
help.data.* page. Distinct strings keep the dedup invariant intact, and
note_help_topic needs no change — `help insert` now shows the simple block and
the sql_insert block (like `help create` already did), and the advanced-only
forms resolve.

note_help now groups the list by CommandCategory: app-lifecycle commands first
(unlabelled), then "Simple-mode commands:" and "Advanced-mode (SQL) commands:"
sections — replacing the old single "DSL data commands (in simple mode):"
header, which used the banned "DSL" term and mis-labelled the advanced SQL
forms it already contained.

Four new help_command tests (red→green). Recorded as ADR-0024 Amendment 1;
CHANGELOG updated.

docs/adr/0024-unified-grammar-tree-execution-plan.md

@@ -706,6 +706,56 @@ documentation is still hand-curated for round 1.
   table-ident from new-name-ident visually is a future
   enhancement.
 
+## Amendment 1 — advanced-mode SQL forms get their own `help` pages, and the list groups by mode (2026-06-22, issue #36)
+
+`help_id` (§Node taxonomy) drives two surfaces: the `help` **list**
+(`note_help` emits one `help.<id>` block per `Some` id) and the
+`help <topic>` **lookup** (`note_help_topic` shows the block of every
+node whose entry word matches the topic). The dedup rule is that
+`help_id` *strings* are unique (one block ⇒ printed once).
+
+Originally the six advanced-mode SQL **DML/query** forms — `SELECT`,
+`WITH`, `SQL_INSERT`, `SQL_UPDATE`, `SQL_DELETE`, `EXPLAIN_SQL` —
+carried `help_id: None`. That was a list-formatting shortcut (avoid a
+second `insert` entry), but it had a side effect: `help select` /
+`help with` resolved to **nothing** (the unknown-topic note), and
+`help insert` showed only the simple form — even though the SQL surface
+is genuinely different and advanced mode exists precisely for learners
+moving to raw SQL. (The advanced SQL **DDL** forms — `sql_create_table`
+etc. — already had their own `help.ddl.sql_*` pages, so the gap was
+inconsistent as well as a pedagogy hole.)
+
+**Decision.** Give every advanced SQL form its **own** `help_id`
+(`data.select`, `data.with`, `data.sql_insert`, `data.sql_update`,
+`data.sql_delete`, `data.explain_sql`) with a hand-curated
+`help.data.*` page (the catalog body stays hand-written, per "What's
+out of scope" above — this amendment doesn't change that). Because the
+ids are **distinct strings**, the dedup invariant
+(`no_two_registered_commands_share_a_help_id`) is untouched, and:
+
+- **`help <topic>` shows every form sharing the entry word** — so
+  `help insert` shows the simple block *and* the `sql_insert` block
+  (exactly as `help create` already showed the simple + SQL create
+  forms). Advanced-only `help select` / `help with` now resolve.
+- **The list groups by mode.** `note_help` now splits the REGISTRY by
+  [`CommandCategory`]: app-lifecycle commands (ids in the `app.*`
+  namespace, usable in either mode) list first, unlabelled, under the
+  intro; then a **`help.simple_section`** ("Simple-mode commands:")
+  group and a **`help.advanced_section`** ("Advanced-mode (SQL)
+  commands:") group. This replaces the single `help.dsl_section` header
+  ("DSL data commands (in simple mode):"), which both used the banned
+  "DSL" term (ADR-0002 user-facing posture) and wrongly claimed simple
+  mode for the advanced SQL forms the section already held.
+
+This partially realises ADR-0030 §6's "Polish" item (a `help sql`
+page): rather than one combined page, each form has its own, reached
+through the normal `help <topic>` surface and discoverable in the
+advanced-mode list section. `note_help_topic` needed **no** change —
+the new `help_id`s make the forms resolve automatically. Covered by
+`help_command::{help_select_renders_the_sql_select_block,
+help_with_renders_the_cte_block, help_insert_shows_both_simple_and_sql_forms,
+help_list_splits_simple_and_advanced_sections}`.
+
 ## References
 
 - ADR-0023 — Unified declarative grammar tree (Proposed direction). Superseded by this ADR for execution detail.