feat(cli): --version/-V + in-app version command + release guard (ADR-0054)

Cargo.toml version is the single source of truth, surfaced by a
--version/-V CLI flag and an in-app `version` command (both via
cli::version_text -> cli.version_line). release.yaml gains a guard that
fails the release unless the v* tag equals v<CARGO_PKG_VERSION>, keeping
--version, the release name, and the asset in lockstep. New app command
wired across grammar/REGISTRY/dispatch/usage/help/hint-corpus/keys; 6
test-first tests. Also fixes a stale "macOS deferred" comment in
release.yaml. ADR-0054 + README index + plan-doc step 1.

src/app.rs

@@ -1868,6 +1868,12 @@ impl App {
                 self.note_hint_for_recent_error();
                 Vec::new()
             }
+            // ADR-0054: the in-app twin of `--version`. Reports the same
+            // single source of truth (`CARGO_PKG_VERSION`, via cli::version_text).
+            AppCommand::Version => {
+                self.note_system(crate::cli::version_text());
+                Vec::new()
+            }
             AppCommand::Rebuild => vec![Action::PrepareRebuild],
             AppCommand::Save => self.handle_save_command(false),
             AppCommand::SaveAs => self.handle_save_command(true),
@@ -5737,6 +5743,29 @@ mod tests {
         ));
     }
 
+    // ── ADR-0054: in-app `version` command ──────────────────────────
+
+    #[test]
+    fn version_command_parses_to_app_version() {
+        use crate::dsl::{parse_command, AppCommand, Command};
+        assert!(matches!(
+            parse_command("version"),
+            Ok(Command::App(AppCommand::Version))
+        ));
+    }
+
+    #[test]
+    fn version_command_emits_the_cargo_version() {
+        let mut app = App::new();
+        type_str(&mut app, "version");
+        submit(&mut app);
+        assert!(
+            output_contains(&app, env!("CARGO_PKG_VERSION")),
+            "in-app `version` should print CARGO_PKG_VERSION: {}",
+            error_lines(&app),
+        );
+    }
+
     #[test]
     fn hint_command_with_no_recent_error_shows_getting_started() {
         let mut app = App::new();