ae5aee279b
- Changed bd init to always create beads.db instead of {prefix}.db
- Added migration logic to detect and rename old databases
- Updated findDatabaseInTree to prefer beads.db and warn on multiple .db files
- Daemon now refuses to start if multiple .db files exist (ambiguity error)
- Updated tests to expect beads.db instead of prefix-based naming
- Tested migration, ambiguity detection, and warning messages