test+docs: 3k Phase-3 verification sweep — e2e DML + filled cross-cut matrix

Sub-phase 3k of ADR-0033. Adds the Tier-3 end-to-end DML suite (tests/sql_dml_e2e.rs) and the cross-cut gap-fill tests, fills the verification matrix (every row a verified file::function), and produces the phase-exit report.

- tests/sql_dml_e2e.rs: INSERT…SELECT cross-table, all-ten-type multi-row INSERT + RETURNING type recovery, UPDATE-with-subquery-in-SET, cascade DELETE, UPSERT round-trip, RETURNING x3, history.log replay, OOS rejections (full §13 table), validity-indicator-from-SQL-DML.
- walker/mod.rs, highlight.rs, completion.rs, input_render.rs: inherited-diagnostic, DML-keyword highlight, INSERT INTO completion, and advanced-mode DML hint-panel cross-cuts.
- Matrix correction (user-confirmed): predicate warnings fire on row-scoped DML slots; INSERT VALUES has no row scope (ADR-0033 §8.4).
- Auto-snapshot row marked N/A (user-confirmed): ADR-0006 unimplemented for both paths; deferred.

/runda round: added an advanced-mode DML hint-panel test (A6 was attributed to simple-mode prose under the §8 advanced heading); extended OOS coverage to the full ADR-0033 §13 table (OOS-5 INDEXED BY / OOS-6 multi-statement) + a trailing-semicolon guard.

1645 passing / 0 failing / 0 skipped / 1 ignored. Clippy clean.

src/dsl/walker/highlight.rs

@@ -397,4 +397,38 @@ mod tests {
             );
         }
     }
+
+    #[test]
+    fn sql_dml_keywords_classified() {
+        // ADR-0030 §8 / ADR-0033 — the DML entry words and clause
+        // keywords (INSERT / INTO / VALUES / ON / CONFLICT /
+        // RETURNING / UPDATE / SET / DELETE / FROM) all get the
+        // Keyword class in Advanced mode. 3k cross-cut: the
+        // ambient highlighter covers the DML surface, not just
+        // SELECT.
+        let keywords_of = |input: &'static str| -> Vec<&'static str> {
+            run_advanced(input)
+                .into_iter()
+                .filter(|(_, _, c)| *c == HighlightClass::Keyword)
+                .map(|(s, e, _)| &input[s..e])
+                .collect()
+        };
+
+        let insert = keywords_of(
+            "insert into t (a) values (1) on conflict (a) do update set a = excluded.a returning a",
+        );
+        for kw in ["insert", "into", "values", "on", "conflict", "do", "update", "set", "returning"] {
+            assert!(insert.contains(&kw), "INSERT/UPSERT: missing `{kw}`; got {insert:?}");
+        }
+
+        let update = keywords_of("update t set a = 1 where id = 2 returning a");
+        for kw in ["update", "set", "where", "returning"] {
+            assert!(update.contains(&kw), "UPDATE: missing `{kw}`; got {update:?}");
+        }
+
+        let delete = keywords_of("delete from t where id = 1 returning *");
+        for kw in ["delete", "from", "where", "returning"] {
+            assert!(delete.contains(&kw), "DELETE: missing `{kw}`; got {delete:?}");
+        }
+    }
 }