feat(remotion): isolated client-side player (Approach A) — templates render in-browser

Render the React-Three-Fiber-v9 (React 19) templates client-side without touching the
React-18 Next host: a standalone Vite app (services/remotion/player) mounts
@remotion/player with the real FlexStory composition. The studio will embed it via an
iframe and feed scene data (URL hash for first paint, postMessage for live edits).

- player/main.tsx: reads {props, aspect, watermark}, computes duration via
  calcFlexStoryMetadata, renders <Player>. Free tier shows a watermark overlay
  (preview only — clean export stays server-authorized).
- vite.config.player.ts: builds to player-dist/ with relative base (servable at /player/).
- @remotion/player + vite added.

Verified: vite build bundles FlexStory + three.js (672 modules → 1.3MB) and serves
at /player/index.html (200). Browser render to be confirmed.

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

services/remotion/package.json

@@ -17,6 +17,7 @@
     "@react-three/postprocessing": "^3.0.4",
     "@remotion/cli": "4.0.290",
     "@remotion/lottie": "^4.0.290",
+    "@remotion/player": "^4.0.290",
     "@remotion/three": "^4.0.290",
     "@remotion/zod-types": "4.0.290",
     "@types/three": "^0.171.0",
@@ -31,6 +32,8 @@
     "@dicebear/collection": "^9.4.2",
     "@dicebear/core": "^9.4.2",
     "@types/react": "19.0.0",
-    "typescript": "5.5.4"
+    "@vitejs/plugin-react": "^4.7.0",
+    "typescript": "5.5.4",
+    "vite": "^5.4.21"
   }
 }