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/mod.rs

@@ -5154,6 +5154,75 @@ mod tests {
         );
     }
 
+    #[test]
+    fn sql_delete_where_unknown_column_is_error() {
+        // 3k cross-cut (matrix I3): schema-existence fires on a
+        // top-level DELETE's WHERE, not only on INSERT/UPDATE slots.
+        let schema = schema_with("t", &[("id", Type::Int), ("v", Type::Int)]);
+        let diags = diag_keys("delete from t where nonexistent = 1", &schema);
+        assert!(
+            diags.iter().any(|d| d.contains("no such column")),
+            "expected unknown_column on the DELETE WHERE; got {diags:?}",
+        );
+    }
+
+    #[test]
+    fn sql_update_where_unknown_column_is_error() {
+        // 3k cross-cut (matrix I3): schema-existence fires on a
+        // top-level UPDATE's WHERE (the SET case is covered by
+        // `sql_update_unknown_set_column_is_error`).
+        let schema = schema_with("t", &[("id", Type::Int), ("v", Type::Int)]);
+        let diags = diag_keys("update t set v = 1 where nonexistent = 1", &schema);
+        assert!(
+            diags.iter().any(|d| d.contains("no such column")),
+            "expected unknown_column on the UPDATE WHERE; got {diags:?}",
+        );
+    }
+
+    #[test]
+    fn sql_delete_where_like_numeric_warns() {
+        // 3k cross-cut (matrix I6): the like_numeric predicate
+        // warning fires on a DELETE's WHERE (the prior coverage was
+        // SELECT / HAVING / CASE only).
+        let schema = schema_with("t", &[("id", Type::Int), ("count", Type::Int)]);
+        let diags = diag_keys("delete from t where count like 5", &schema);
+        assert!(
+            diags.iter().any(|d| d.contains("LIKE")),
+            "expected like_numeric warning on the DELETE WHERE; got {diags:?}",
+        );
+    }
+
+    #[test]
+    fn sql_update_set_case_predicate_warns() {
+        // 3k cross-cut (matrix I7, corrected): a predicate warning
+        // fires inside a CASE in an UPDATE SET RHS — a row-scoped
+        // DML sql_expr slot (ADR-0033 §8.4 — "WHERE and CASE").
+        let schema = schema_with("t", &[("id", Type::Int), ("v", Type::Int)]);
+        let diags = diag_keys(
+            "update t set v = case when v = NULL then 1 else 0 end where id = 1",
+            &schema,
+        );
+        assert!(
+            diags.iter().any(|d| d.contains("IS NULL")),
+            "expected eq_null warning inside the UPDATE SET CASE; got {diags:?}",
+        );
+    }
+
+    #[test]
+    fn insert_select_where_predicate_warns() {
+        // 3k cross-cut (matrix I7, corrected): the predicate-warning
+        // pass fires on the WHERE of an INSERT … SELECT row source
+        // (`b.total` is real, so `like 5` is a numeric LIKE). Plain
+        // INSERT VALUES carries no row scope, so the realizable
+        // claim is the INSERT … SELECT slot, not VALUES.
+        let schema = two_table_schema(); // a(id,name), b(id,total real)
+        let diags = diag_keys("insert into a (id) select id from b where total like 5", &schema);
+        assert!(
+            diags.iter().any(|d| d.contains("LIKE")),
+            "expected like_numeric on the INSERT…SELECT WHERE; got {diags:?}",
+        );
+    }
+
     #[test]
     fn cte_name_is_valid_table_source() {
         let schema = schema_with("base", &[("id", Type::Int)]);