Add comprehensive unit tests for all command handlers:
- TestHelperFunctions: is_group, get_group_id, get_user_id, get_room_id
- TestCmdBounty: lists bounties, handles empty
- TestCmdMy: shows tracked in groups, personal in DM
- TestCmdAdd: add bounty success, validation
- TestCmdUpdate: update bounty, permission denied, invalid ID
- TestCmdDelete: delete bounty, invalid ID
- TestCmdTrack: track in group, reject in DM
- TestCmdUntrack: untrack in group, reject in DM
- TestCmdStart: group vs DM behavior
- TestCmdHelp: shows all commands
Also fix conftest.py to remove obsolete fresh_db fixture
that referenced non-existent db module.
All 55 tests pass.
Addresses han's feedback on PR #33
0c36aa7b88