feat: add Remotion entry point with registerRoot()

The project was missing a proper Remotion entry file that calls
registerRoot(). This is required by `remotion lambda sites create`
to bundle and deploy the site to S3.

remotion/index.ts only re-exports components — it doesn't register
the root. This new entry.ts is the correct entry point for Lambda
deploys and Remotion Studio.

Author: codercatdev

remotion/entry.ts

@@ -0,0 +1,4 @@
+import { registerRoot } from "remotion";
+import { RemotionRoot } from "./Root";
+
+registerRoot(RemotionRoot);