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/grammar/data.rs

@@ -20,7 +20,7 @@ use crate::dsl::command::{Command, Expr, RowFilter};
 use crate::dsl::grammar::{
     CommandNode, IdentSource, Node, NumberValidator, ValidationError, Word, expr,
     shared::{column_value_list, current_column_value},
-    sql_insert, sql_select, sql_update,
+    sql_delete, sql_insert, sql_select, sql_update,
 };
 use crate::dsl::walker::context::WalkContext;
 use crate::dsl::value::Value;
@@ -952,6 +952,39 @@ fn build_sql_update(path: &MatchedPath, source: &str) -> Result<Command, Validat
     Ok(Command::SqlUpdate { sql, target_table })
 }
 
+/// Build `Command::SqlDelete` from a validated SQL `DELETE`
+/// (ADR-0033 §1/§7, sub-phase 3f). Extracts the target table from
+/// the matched path so the worker re-persists the right CSV and
+/// snapshots the right inbound children for cascade diffing. No
+/// WHERE clause is captured — the worker executes the verbatim SQL
+/// and never inspects the predicate (Amendment 2).
+///
+/// Dev-scaffold detail: the entry word is `sql_delete` (not valid
+/// SQL), so the statement is reconstructed as `delete` + the matched
+/// tail (which opens at `from`). Sub-phase 3j wires the real
+/// `delete` entry word, at which point this collapses to
+/// `source.trim()`.
+fn build_sql_delete(path: &MatchedPath, source: &str) -> Result<Command, ValidationError> {
+    // The DELETE target is the first `table_name` ident (it precedes
+    // any table referenced inside a WHERE subquery).
+    let target_table = path
+        .items
+        .iter()
+        .find_map(|item| match item.kind {
+            MatchedKind::Ident {
+                role: "table_name", ..
+            } => Some(item.text.clone()),
+            _ => None,
+        })
+        .unwrap_or_default();
+    let tail = path
+        .items
+        .first()
+        .map_or(source, |entry| &source[entry.span.1..]);
+    let sql = format!("delete {}", tail.trim());
+    Ok(Command::SqlDelete { sql, target_table })
+}
+
 // =================================================================
 // CommandNodes
 // =================================================================
@@ -1061,6 +1094,23 @@ pub static SQL_UPDATE: CommandNode = CommandNode {
     usage_ids: &[],
 };
 
+/// SQL `DELETE` development scaffold (ADR-0033 sub-phase 3f).
+///
+/// Registered under the temporary entry word `sql_delete` so the
+/// SQL DELETE grammar and execution path (including cascade-summary
+/// parity) can be exercised in isolation, WITHOUT yet making
+/// `delete` a shared DSL/SQL entry word. Sharing `delete` is
+/// sub-phase 3j. This scaffold (entry word + reconstruction in
+/// `build_sql_delete`) is removed when 3j wires the real `delete`
+/// entry word.
+pub static SQL_DELETE: CommandNode = CommandNode {
+    entry: Word::keyword("sql_delete"),
+    shape: Node::Subgrammar(&sql_delete::SQL_DELETE_SHAPE),
+    ast_builder: build_sql_delete,
+    help_id: None,
+    usage_ids: &[],
+};
+
 // =================================================================
 // Tests — `explain` grammar (ADR-0028 §1)
 // =================================================================