grammar+db: 3f — SQL DELETE + cascade summary (ADR-0033 §1/§7)

New src/dsl/grammar/sql_delete.rs (FROM <table> [WHERE] [;]),
Command::SqlDelete, Request::RunSqlDelete, do_sql_delete worker.

do_sql_delete mirrors the DSL do_delete: detect FK cascade by
before/after child row-count diffing, re-persist target + every
cascade-affected child, history-on-success inside the tx. Reuses
CommandOutcome::Delete -> handle_dsl_delete_success, so the
per-relationship cascade summary formatter is shared, not duplicated.

ADR-0033 Amendment 2: supersedes §7's WHERE-injected pre-count. Its
premise (DSL handler builds pre-counts from the typed Expr) was wrong
— do_delete uses count-diff. The pre-count would also have broken the
§2 parity promise by reporting SET NULL the DSL path doesn't. Count-
diff gives exact parity, no WHERE-byte extraction, and withdraws R2.
SET NULL reporting deferred for both paths (user-confirmed).

Tests: +6 grammar unit, +12 integration (cascade parity with DSL,
both R2 subquery cases, before-execute order, no-WHERE, FK-rejection
rollback, childless-parent, two-child cascade). 1542 pass / 0 fail /
1 ignored. Clippy clean. Dev sql_delete entry word removed in 3j.

src/runtime.rs

@@ -1902,6 +1902,16 @@ async fn execute_command_typed(
             .run_sql_update(sql, src, target_table)
             .await
             .map(CommandOutcome::Update),
+        // A SQL `DELETE` (advanced mode; ADR-0033 §1/§7). Grammar-
+        // as-text: the worker runs the validated `sql`, detects FK
+        // cascade by row-count diffing, and re-persists the target
+        // plus every cascade-affected child. Reuses the DSL delete
+        // outcome (affected-row count + per-relationship cascade
+        // summary).
+        Command::SqlDelete { sql, target_table } => database
+            .run_sql_delete(sql, src, target_table)
+            .await
+            .map(CommandOutcome::Delete),
         // `EXPLAIN QUERY PLAN` never executes the wrapped
         // statement (ADR-0028 §2), so explaining a destructive
         // command is safe. `src` is unused here — explain is a