Lifecycle hooks: @OnStart/@OnQuit, @OnDespawn, @OnAttach (like @OnSpawn)

Adds the rest of the game/entity/property lifecycle as @-hooks, each firing at
one timeline moment and reducing to ordinary code:

- @OnStart / @OnQuit (program): @OnStart aliases the Start phase; @OnQuit runs in
  the frame loop's done: block, after the loop stops and before teardown.
- @OnDespawn(Model) (entity): a destructor. Despawn doesn't statically know the
  entity's model, so hooks compile to @on_despawn_<Model>(entity) functions and
  emit_despawn dispatches on @L_kind. Symmetric with @OnSpawn.
- @OnAttach(Property): fires in emit_init_component once a property is attached
  and seeded, with the property bound by name.

Registries + parsing mirror @OnSpawn. examples/lifecycle.ludic narrates the whole
timeline (output 1 700 50 950 2). Behaviour-preserving (goldens byte-identical,
despawn users unaffected when no hooks registered); test.sh 16/16, fixpoint holds.

Deferred: @OnDetach (per-property runtime dispatch) and scene @OnEnter/@OnExit
(need scene support in the compiler).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

test.sh

@@ -56,6 +56,11 @@ if ./selfhost/game-build.sh build/ludicc examples/annotations.ludic "/tmp/ludic_
    && [ "$(/tmp/ludic_ann </dev/null | tr '\n' ' ')" = "3 25 0 0 " ]; then
   ok "annotations.ludic (@Queries / @Computed / @OnSpawn / @Handles)"
 else bad "annotations: $(tail -1 /tmp/ann.out)"; fi
+# Lifecycle hooks fire in timeline order: @OnStart @OnAttach @OnSpawn @OnDespawn @OnQuit.
+if ./selfhost/game-build.sh build/ludicc examples/lifecycle.ludic "/tmp/ludic_life" >/tmp/life.out 2>&1 \
+   && [ "$(/tmp/ludic_life </dev/null | tr '\n' ' ')" = "1 700 50 950 2 " ]; then
+  ok "lifecycle.ludic (@OnStart/@OnAttach/@OnSpawn/@OnDespawn/@OnQuit in order)"
+else bad "lifecycle: $(tail -1 /tmp/life.out)"; fi
 # --- Toolchain-agent CLI smoke tests append below this line ---
 echo "== self-hosted front-end binaries (ludicc / ludic) =="
 # The two commands are one multi-call native binary built from the seed with