feat(goals): add cinematic celebration sequence

TODO.md

@@ -19,7 +19,7 @@ The largest gap between this and a AAA-feeling product is presentation, not code
 - [x] VFX on anything that moves: throttle-reactive engine cores and plumes, distinct turbo flames, a speed-scaled ball trail, contact sparks and team-tinted goal bursts.
 - [x] Impact feedback — intensity-scaled screen shake, unscaled hit-stop, HUD flash and controller rumble on ball contact.
 - [x] Camera feel in `ship_camera.gd` — speed-based FOV widening, turbo kick-back and decaying impact shake.
-- [ ] Goal celebration sequence: today it's a `print()` and a label scale-pop. Wants an explosion, team-tinted screen flash, camera cut, slow-mo, title card. `HUDController`'s `ResultOverlay` animation is a reasonable template.
+- [x] Goal celebration sequence: goal burst, team-tinted flash/title card, dedicated camera cut and slow-motion beat after authoritative score registration and before reset/kickoff.
 - [x] Local lighting / dynamic GI — four local pitch lights plus SDFGI provide bounce and contact lighting for the runtime-generated arena shell; the shader's `hull_fill` stand-in is retired. (The shell is generated in `_ready`, so it cannot participate in an editor LightmapGI bake.)
 - [x] Dress `arena_03` — its asteroid field now has mining stations, debris clusters and a distant planet.
 - [ ] Custom font + a real `Theme` resource for the HUD. The procedural instruments are well-engineered, but `ThemeDB.fallback_font` at 10-13 px reads as a debug overlay.