Implements bd-121: Global daemon with system-wide socket
Changes:
- Add --global flag to daemon command
- Use ~/.beads/bd.sock when --global is set
- Skip git repo validation for global daemon
- Update daemon discovery to check ~/.beads/ as fallback
- Both Go CLI and Python MCP client check global socket
- Update all tests to pass global parameter
Benefits:
- Single daemon serves all repos on system
- No per-repo daemon management needed
- Better resource usage for users with many repos
- Automatic fallback when local daemon not running
Usage:
bd daemon --global # Start global daemon
bd daemon --status --global # Check global status
bd daemon --stop --global # Stop global daemon
Related: bd-73 (multi-repo epic)
Amp-Thread-ID: https://ampcode.com/threads/T-ea606216-b886-4af0-bba8-56d000362d01
Co-authored-by: Amp <amp@ampcode.com>