feat(hint): H2 Phase C batch 3 — DML tier-3 hints (ADR-0053)

Per-form hints for querying/changing data: update, delete, show
data/table/tables/relationships/indexes, seed, explain, replay
(insert was the Phase-B exemplar). hint_ids wired on UPDATE/DELETE/
SHOW/SEED/EXPLAIN/REPLAY; catalogue + keys.rs registered. +2 spot
tests (incl. multi-form SHOW disambiguation); 2493 pass / 1 ignored,
clippy clean.

src/dsl/grammar/data.rs

@@ -1790,7 +1790,13 @@ pub static SHOW: CommandNode = CommandNode {
     shape: SHOW_SHAPE,
     ast_builder: build_show,
     help_id: Some("data.show"),
-    hint_ids: &[],
+    hint_ids: &[
+        "show_data",
+        "show_table",
+        "show_tables",
+        "show_relationships",
+        "show_indexes",
+    ],
     usage_ids: &[
         "parse.usage.show_data",
         "parse.usage.show_table",
@@ -1806,7 +1812,7 @@ pub static SEED: CommandNode = CommandNode {
     shape: SEED_SHAPE,
     ast_builder: build_seed,
     help_id: Some("data.seed"),
-    hint_ids: &[],
+    hint_ids: &["seed"],
     usage_ids: &["parse.usage.seed"],
 };
 
@@ -1824,7 +1830,7 @@ pub static UPDATE: CommandNode = CommandNode {
     shape: UPDATE_SHAPE,
     ast_builder: build_update,
     help_id: Some("data.update"),
-    hint_ids: &[],
+    hint_ids: &["update"],
     usage_ids: &["parse.usage.update"],};
 
 pub static DELETE: CommandNode = CommandNode {
@@ -1832,7 +1838,7 @@ pub static DELETE: CommandNode = CommandNode {
     shape: DELETE_SHAPE,
     ast_builder: build_delete,
     help_id: Some("data.delete"),
-    hint_ids: &[],
+    hint_ids: &["delete"],
     usage_ids: &["parse.usage.delete"],};
 
 pub static REPLAY: CommandNode = CommandNode {
@@ -1840,7 +1846,7 @@ pub static REPLAY: CommandNode = CommandNode {
     shape: REPLAY_PATH,
     ast_builder: build_replay,
     help_id: Some("data.replay"),
-    hint_ids: &[],
+    hint_ids: &["replay"],
     usage_ids: &["parse.usage.replay"],};
 
 pub static EXPLAIN: CommandNode = CommandNode {
@@ -1848,7 +1854,7 @@ pub static EXPLAIN: CommandNode = CommandNode {
     shape: EXPLAIN_SHAPE,
     ast_builder: build_explain,
     help_id: Some("data.explain"),
-    hint_ids: &[],
+    hint_ids: &["explain"],
     usage_ids: &["parse.usage.explain"],};
 
 /// `explain` over advanced-mode SQL (ADR-0039).