Implements single-shot mode improvements for Windows and Docker scenarios:
- Add --lock-timeout global flag (default 30s, 0 = fail immediately)
- Add config file support: lock-timeout: 100ms
- Parameterize SQLite busy_timeout via NewWithTimeout() function
- In --sandbox mode: default lock-timeout to 100ms
- In --sandbox mode: skip FlushManager creation (no background goroutines)
This addresses bd.exe hanging on Windows and locking conflicts when
using beads across host + Docker containers.
Closes: bd-59er, bd-r4od, bd-dh8a
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
fc23dca7fb