When recording which team members beat a boss, users must manually enter a level for each pokemon. Since the app does not track levels anywhere else, this is unnecessary friction with no payoff.
## Current Implementation
- Level input in `BossDefeatModal.tsx:200-211`
- DB column `boss_result_team.level` is `SmallInteger NOT NULL` (in `models.py`)
- Level is required in the API schema
## Proposed Solution
Remove the level field entirely from the UI and make it optional in the backend: