docs: ADR-0036 revised to surgical "validate-and-retain"; +X4/X5 open questions

Narrow ADR-0036 from "bind literals via the DSL path" to "validate literal
values (shared validators) + retain them; execute verbatim, keep auto-fill
and command identity mode-specific" — after a concrete auto-fill difference
(non-PK serial) confirmed the modes aren't identical even for single-row
literals. Augments (no longer supersedes) ADR-0030 §4 / ADR-0033 §10;
Amendment 3 stands. README + forward-notes on 0030/0033 updated. Records
requirements.md X4 (serial auto-fill — possible bug) and X5 (framework
cohesion / share-mechanics-not-commands).

docs/adr/0033-sql-dml-grammar.md

@@ -10,15 +10,19 @@ for the phase-exit report and the filled cross-cut matrix in
 `docs/plans/20260520-adr-0033-phase-3.md`. Amendments 1–3 below
 are part of this acceptance.
 
-> **Forward note (2026-05-26).** The **Proposed ADR-0036** narrows the
-> §10 verbatim-execution model for **literal data values**: rather than
-> handing the user's literal text to the engine, `INSERT`/`UPDATE` should
-> parse literal values to typed `Value`s, validate them, retain them on
-> the command (for binding *and* error enrichment), and bind them as
-> parameters — as the simple-mode DSL already does. Expressions, `WHERE`
-> predicates, `INSERT … SELECT`, `RETURNING`, UPSERT, and `SELECT` stay
-> verbatim text. The `Sql*` command variants and worker handlers remain;
-> only the literal-value execution path changes. Pending acceptance.
+> **Forward note (2026-05-26, ADR-0036 Accepted).** ADR-0036 **augments**
+> the §10 model — it does **not** change verbatim execution and does
+> **not** collapse the two-command identity of **Amendment 3** (which
+> stands). It adds a *value-validation* step: `INSERT`/`UPDATE` literal
+> values are parsed to typed `Value`s, **validated** against the column
+> type (sharing the DSL's validators), and **retained** on the command
+> (so a constraint error can show the offending value) — then the
+> statement still executes **verbatim**. `Command::SqlInsert` gains a
+> captured-literals payload; its execution and `plan_shortid_autofill`
+> are unchanged. Expressions, `WHERE`, `INSERT … SELECT`, `RETURNING`,
+> UPSERT, and `SELECT` are untouched. (The serial/shortid auto-fill
+> difference vs simple mode is tracked separately as `requirements.md`
+> X4.)
 
 ## Context