### CHANGES
- Introduce `cmd` directory for all main application binaries.
- Move all Go packages into the `internal` directory.
- Rename the `restapi` package to `server` for clarity.
- Consolidate patterns and strategies into a new `data` directory.
- Group all auxiliary scripts into a new `scripts` directory.
- Move all documentation and images into a `docs` directory.
- Update all Go import paths to reflect the new structure.
- Adjust CI/CD workflows and build commands for new layout.
## CHANGES
- Add new YouTube handler for transcript requests
- Create `/youtube/transcript` POST endpoint route
- Add request/response types for YouTube API
- Support language and timestamp options
- Update frontend to use new endpoint
- Remove chat endpoint dependency for transcripts
- Validate video vs playlist URLs properly