feat: Update local agent documentation to reflect changes in user_id and session_id handling; add marketing strategy document; update skills-lock.json with new Remotion best practices; update website subproject commit.

.claude/skills/remotion-best-practices/rules/ffmpeg.md

@@ -0,0 +1,34 @@
+---
+name: ffmpeg
+description: Using FFmpeg and FFprobe in Remotion
+metadata:
+  tags: ffmpeg, ffprobe, video, trimming
+---
+
+## FFmpeg in Remotion
+
+`ffmpeg` and `ffprobe` do not need to be installed. They are available via the `npx remotion ffmpeg` and `npx remotion ffprobe`:
+
+```bash
+npx remotion ffmpeg -i input.mp4 output.mp3
+npx remotion ffprobe input.mp4
+```
+
+### Trimming videos
+
+You have 2 options for trimming videos:
+
+1. **Preferred**: Use the `trimBefore` and `trimAfter` props of the `<Video>` component. This is non-destructive, requires no re-encoding, and you can change the trim at any time.
+
+```tsx
+import {Video} from '@remotion/media';
+
+<Video src={staticFile('video.mp4')} trimBefore={5 * fps} trimAfter={10 * fps} />;
+```
+
+2. Use the FFmpeg command line. You MUST re-encode the video to avoid frozen frames at the start of the video. Only use this if you need a standalone trimmed file (e.g. for upload or external use).
+
+```bash
+# Re-encodes from the exact frame
+npx remotion ffmpeg -ss 00:00:05 -i public/input.mp4 -to 00:00:10 -c:v libx264 -c:a aac public/output.mp4
+```