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/dsl/command.rs

@@ -320,6 +320,18 @@ pub enum Command {
         sql: String,
         target_table: String,
     },
+    /// A SQL `DELETE` validated by the walker (ADR-0033 §1/§7,
+    /// advanced mode). Grammar-as-text: the worker executes `sql`,
+    /// observes any FK cascade by row-count diffing (Amendment 2 —
+    /// the same mechanism the DSL `do_delete` uses), and re-persists
+    /// `target_table`'s CSV plus every cascade-affected child
+    /// (ADR-0030 §11). The worker never inspects the WHERE clause, so
+    /// no predicate is carried here. `RETURNING` (3g) is added by the
+    /// sub-phase that reads it.
+    SqlDelete {
+        sql: String,
+        target_table: String,
+    },
     /// App-lifecycle command (per ADR-0003). These work in both
     /// simple and advanced modes; the dispatcher branches on the
     /// `Command::App(...)` variant before mode-specific routing.
@@ -617,6 +629,7 @@ impl Command {
             Self::Select { .. } => "select",
             Self::SqlInsert { .. } => "insert into",
             Self::SqlUpdate { .. } => "update",
+            Self::SqlDelete { .. } => "delete from",
             Self::App(app) => match app {
                 AppCommand::Quit => "quit",
                 AppCommand::Help => "help",
@@ -687,7 +700,8 @@ impl Command {
             // A SQL `INSERT` carries its parsed target table (for
             // CSV re-persistence and ok-summary subject).
             Self::SqlInsert { target_table, .. }
-            | Self::SqlUpdate { target_table, .. } => target_table,
+            | Self::SqlUpdate { target_table, .. }
+            | Self::SqlDelete { target_table, .. } => target_table,
             // App commands aren't tied to schema entities — the
             // verb is the most identifying thing. The
             // display_subject override below provides a richer