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.

tests/typing_surface/mod.rs

@@ -251,6 +251,7 @@ fn command_kind_label(cmd: &rdbms_playground::dsl::Command) -> String {
             AppCommand::Quit => "App(Quit)".into(),
             AppCommand::Help { .. } => "App(Help)".into(),
             AppCommand::Hint => "App(Hint)".into(),
+            AppCommand::Version => "App(Version)".into(),
             AppCommand::Rebuild => "App(Rebuild)".into(),
             AppCommand::Save => "App(Save)".into(),
             AppCommand::SaveAs => "App(SaveAs)".into(),