grammar+db: 3g — RETURNING on INSERT/UPDATE/DELETE (ADR-0033 §5)

Shared RETURNING_CLAUSE (reuses Phase-2 PROJECTION_LIST, now
pub(crate)) as an optional tail on all three SQL DML shapes.
`returning: bool` on the Command variants, set by the ast-builders
and threaded to the worker. run_returning collects the returned rows
as a DataResult (RETURNING mutates + yields in one pass), reusing
resolve_select_column_types for bare-column type recovery; computed
projections stay typeless. DeleteResult gains a `data` field rendered
alongside the cascade summary.

Follow-set fix: `returning` is added to the table-source and
projection bare-alias follow-sets so an INSERT … SELECT row source
stops before RETURNING instead of reading it as a table alias.

Auto-fill × RETURNING: build_sql_insert stops row_source before the
RETURNING token (keeping it preparable for shortid materialisation),
and plan_shortid_autofill re-appends the RETURNING tail so generated
shortids surface in RETURNING *.

Tests (+17): grammar accept on all three; INSERT/UPDATE/DELETE
RETURNING incl. *, aliases, multi-row, type recovery + computed-
typeless; auto-fill × RETURNING (single + multi-row distinct ids);
INSERT…SELECT…RETURNING execution; UPDATE…RETURNING zero-match;
DELETE…RETURNING cascade+rows; app-level render of both. Dev
sql_insert/sql_update/sql_delete entry words still removed in 3j.
1562 pass / 0 fail / 1 ignored. Clippy clean.

src/dsl/grammar/sql_delete.rs

@@ -17,7 +17,7 @@
 //! later. The worker never inspects the WHERE clause (Amendment 2),
 //! so no predicate-byte extraction is needed.
 
-use crate::dsl::grammar::sql_select::{WHERE_CLAUSE, reject_internal_table};
+use crate::dsl::grammar::sql_select::{RETURNING_CLAUSE, WHERE_CLAUSE, reject_internal_table};
 use crate::dsl::grammar::{IdentSource, Node, Word};
 
 /// The `DELETE` target table. `__rdbms_*` rejected (ADR-0030 §6 /
@@ -48,6 +48,7 @@ static SQL_DELETE_TAIL_NODES: &[Node] = &[
     Node::Word(Word::keyword("from")),
     TARGET_TABLE,
     Node::Optional(&WHERE_CLAUSE),
+    Node::Optional(&RETURNING_CLAUSE),
     Node::Optional(&Node::Punct(';')),
 ];
 
@@ -123,6 +124,14 @@ mod tests {
         good("from orders where customer_id in (select id from customers where country = 'DE')");
     }
 
+    #[test]
+    fn returning_tail_admitted() {
+        // 3g: optional RETURNING projection_list tail.
+        good("from orders where id = 1 returning *");
+        good("from orders returning id, total");
+        good("from orders where id = 1 returning id as gone;");
+    }
+
     #[test]
     fn internal_target_table_rejected() {
         bad("from __rdbms_playground_columns");