feat: AI-generated shorts render pipeline

- Remotion composition (ShortsVideo) renders 1080x1920 9:16 shorts
  from script segments (hook/setup/conflict/insight/cta) with animated
  gradient background, word-by-word captions, progress bar
- render-worker.mjs: standalone poller (systemd hermyhq-render.service)
  TTS via edge-tts → Remotion render via Chrome headless → ffmpeg mux +
  thumbnail; ≤60s gate; marks YoutubeScript rendered
- API: POST /api/youtube/render (queue approved→render_queued),
  GET status, GET /render/file (stream video/thumb with Range support)
- Schema: YoutubeScript.videoUrl/thumbnailUrl + YoutubeRender model
- UI: youtube tab gains Renders view (preview/review/approve/reject/
  download), Render Shorts button on approved scripts
- Prisma db push applied to prod DB

src/remotion/index.tsx

@@ -0,0 +1,26 @@
+import { registerRoot, Composition } from "remotion";
+import { ShortsVideo, useTotalDuration } from "./ShortsVideo";
+
+const DEFAULT_SEGMENTS = [
+  { text: "Demo shorts — configure --props to customize.", duration: 60 },
+];
+
+const Shorts: React.FC = () => {
+  return (
+    <Composition
+      id="Shorts"
+      component={ShortsVideo as any}
+      durationInFrames={60}
+      fps={30}
+      width={1080}
+      height={1920}
+      defaultProps={{ segments: DEFAULT_SEGMENTS }}
+      calculateMetadata={({ props }) => {
+        const segs = props.segments?.length ? props.segments : DEFAULT_SEGMENTS;
+        return { durationInFrames: useTotalDuration(segs) };
+      }}
+    />
+  );
+};
+
+registerRoot(Shorts);