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/runtime.rs

@@ -1890,16 +1890,21 @@ async fn execute_command_typed(
             target_table,
             listed_columns,
             row_source,
+            returning,
         } => database
-            .run_sql_insert(sql, src, target_table, listed_columns, row_source)
+            .run_sql_insert(sql, src, target_table, listed_columns, row_source, returning)
             .await
             .map(CommandOutcome::Insert),
         // A SQL `UPDATE` (advanced mode; ADR-0033 §2). Grammar-as-
         // text: the worker runs the validated `sql` and re-persists
         // the parsed `target_table`'s CSV. Reuses the DSL update
         // outcome (affected-row count).
-        Command::SqlUpdate { sql, target_table } => database
-            .run_sql_update(sql, src, target_table)
+        Command::SqlUpdate {
+            sql,
+            target_table,
+            returning,
+        } => database
+            .run_sql_update(sql, src, target_table, returning)
             .await
             .map(CommandOutcome::Update),
         // A SQL `DELETE` (advanced mode; ADR-0033 §1/§7). Grammar-
@@ -1908,8 +1913,12 @@ async fn execute_command_typed(
         // 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)
+        Command::SqlDelete {
+            sql,
+            target_table,
+            returning,
+        } => database
+            .run_sql_delete(sql, src, target_table, returning)
             .await
             .map(CommandOutcome::Delete),
         // `EXPLAIN QUERY PLAN` never executes the wrapped