feat(gacha): refine beta wish animation and SSS reveal

renderer/README.md

@@ -68,11 +68,18 @@ only draws it.
 
 `POST /api/gachabeta` takes the same body and returns the same response as
 `/api/gacha`, rendering an 8-second beta style instead: a cosmic, astrology
-themed night sky in toon shading (flat colour bands, no outlines) seen through
-a perspective action camera. The camera dollies toward a hero cloud, a comet
-lights its rim from behind and bursts through it, the camera chases the comet
-as its flare builds, and after the burst the label appears with a rank
-(`S`, `SS`, `SSS` for rarity 3, 4, 5).
+themed night sky with toon-shaded clouds and stars, without outlines, seen
+through a perspective action camera:
+
+1. The sky fades in around a main cloud. A comet approaches from behind,
+   lights the cloud's rim, then punches through it with scattered puffs and an impact ring.
+2. The camera follows the flying star as its light and lens flare intensify,
+   ending in a starburst and white flash.
+3. The food label appears inside an astrology ring with rank `SSS`.
+
+The caller randomly chooses the food and sends it as `label` (for example,
+`"Bún bò"`). The beta reveal always shows `SSS`; `rarity` still chooses the
+comet's blue, purple, or gold palette. `/api/gacha` keeps its existing ranks.
 
 Response is a silent H.264 `video/mp4` (Telegram plays it as an animation)
 with `X-Gacha-Rarity` and `X-Render-Duration-Ms` headers. Both routes share the