Help: consume CommandNode.help_id — REGISTRY-driven in-app help

Every CommandNode declared a help_id that nothing read; the in-app
`help` body was a single hand-kept catalog block that drifted from
the command set (handoff-12 §2.1).

note_help now iterates the command REGISTRY and translates each
CommandNode's help_id (`help.<id>`), framed by help.intro /
help.dsl_section / help.types_reference. A newly-registered command
appears in `help` automatically — no edit to note_help or a hand-kept
list. Added 20 per-command help entries plus the 3 framing entries;
removed help.in_app_body.

Per-command entries use block scalars: a libyml 0.0.5 scanner bug
panics on long internal space runs in double-quoted scalars, and the
entries are space-aligned.

src/friendly/keys.rs

@@ -120,7 +120,31 @@ pub const KEYS_AND_PLACEHOLDERS: &[(&str, &[&str])] = &[
     ),
     // ---- Help text ----
     ("help.cli_banner", &[]),
-    ("help.in_app_body", &[]),
+    // In-app `help` — framing + per-command entries keyed by
+    // each CommandNode's `help_id` (ADR-0024 §help_id).
+    ("help.intro", &[]),
+    ("help.dsl_section", &[]),
+    ("help.types_reference", &[]),
+    ("help.app.quit", &[]),
+    ("help.app.help", &[]),
+    ("help.app.rebuild", &[]),
+    ("help.app.save", &[]),
+    ("help.app.new", &[]),
+    ("help.app.load", &[]),
+    ("help.app.export", &[]),
+    ("help.app.import", &[]),
+    ("help.app.mode", &[]),
+    ("help.app.messages", &[]),
+    ("help.ddl.create", &[]),
+    ("help.ddl.drop", &[]),
+    ("help.ddl.add", &[]),
+    ("help.ddl.rename", &[]),
+    ("help.ddl.change", &[]),
+    ("help.data.show", &[]),
+    ("help.data.insert", &[]),
+    ("help.data.update", &[]),
+    ("help.data.delete", &[]),
+    ("help.data.replay", &[]),
     // ---- Hint panel ambient typing assistance (ADR-0022 §6) ----
     ("hint.ambient_complete", &[]),
     (