Sync was a bootstrap command that ran `git submodule update` and `uv tool install` for each program. Neither machine uses git submodules anymore, and the install functionality is already available as a program action (`POST /programs/{name}/install`).
Removed files:
- cli/src/castle_cli/commands/sync.py
Updated files:
- cli/src/castle_cli/main.py (removed sync subparser and dispatch)
- README.md (removed sync from Quick Start and CLI reference)