Refactor duel command and related views

- Removed the old duel command implementation in `duel_v2.py`.
- Updated the duel command references in tests to use the new `Duel` class.
- Improved error handling in `fish_profit.py` for price type selection.
- Enhanced combat views in `combat_views.py` to support testing with minimal stubs for Discord UI components.
- Updated database schema for weapons.
- Cleaned up test fixtures in `test_duel_fixtures.py` for better maintainability and flexibility.

Author: PrettyNeet