feat: Phase 4 — replace @remotion/bundler + @remotion/renderer with Puppeteer + FFmpeg

- Created src/engine/renderer/puppeteerRenderer.ts (frame capture via headless Chrome)
- Created src/engine/renderer/videoEncoder.ts (FFmpeg CLI wrapper for MP4/WebM)
- Created src/pages/RenderPage.tsx (headless render page with __BRADLY_RENDER__ API)
- Rewrote src/server/renderQueue.ts — zero Remotion imports
- Deleted scripts/bundle-remotion.js
- Replaced @remotion/bundler + @remotion/renderer with puppeteer-core
- Added renderMode detection in main.tsx entry point

Zero Remotion dependencies remain. Fully independent.

package.json

@@ -15,7 +15,6 @@
     "preview": "vite preview",
     "clean": "rm -rf dist out server.js",
     "lint": "tsc --noEmit",
-    "remotion:bundle": "echo 'Remotion bundle step removed — using Bradly Engine'",
     "package": "npm run build && electron-forge package",
     "make": "npm run build && electron-forge make"
   },
@@ -23,8 +22,7 @@
     "@dnd-kit/core": "^6.3.1",
     "@dnd-kit/utilities": "^3.2.2",
     "@google/genai": "^2.4.0",
-    "@remotion/bundler": "^4.0.468",
-    "@remotion/renderer": "^4.0.468",
+    "puppeteer-core": "^24.9.0",
     "@tailwindcss/vite": "^4.1.14",
     "@vitejs/plugin-react": "^5.0.4",
     "dotenv": "^17.2.3",