feat(remotion): implement Remotion Lambda rendering service

- Full @remotion/lambda integration (renderMediaOnLambda + getRenderProgress)
- Parallel rendering of MainVideo (16:9) and ShortVideo (9:16)
- Progress polling with milestone logging (10%, 25%, 50%, 75%, 90%)
- 15-minute timeout with descriptive error messages
- deployRemotionLambda() one-time setup helper (deploySite + deployFunction)
- Input props mapping from pipeline format to Remotion VideoInputProps
- Added @remotion/lambda dependency

Co-authored-by: video <video@miriad.systems>

Author: Miriad