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/app.rs

@@ -1485,6 +1485,12 @@ impl App {
             C::SqlUpdate { target_table, .. } => {
                 (Operation::Update, Some(target_table.as_str()), None)
             }
+            // A SQL `DELETE` (ADR-0033 §1/§7) — route engine errors
+            // (e.g. an FK violation with no cascade) through the
+            // delete operation with the parsed target.
+            C::SqlDelete { target_table, .. } => {
+                (Operation::Delete, Some(target_table.as_str()), None)
+            }
             C::Replay { .. } => (Operation::Replay, None, None),
             // An `explain` failure (e.g. unknown table) is best
             // described by the wrapped query it failed to plan.