Add Move Animals form with selection context validation and concurrent
change handling via optimistic locking. When selection changes between
client resolution and submit, the user is shown a diff panel and can
confirm to proceed with the current server resolution.
Key changes:
- Add move template with form and diff panel components
- Add move routes (GET /move, POST /actions/animal-move)
- Register move routes in app
- Fix to_xml() usage for HTMLResponse (was using str())
- Use max(current_time, form_ts) for confirmed re-resolution
Tests:
- 15 route tests covering form rendering, success, validation, mismatch
- 7 E2E tests for optimistic lock flow (spec §21.8)
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
