## Bug Fix
- Badge "初めての一歩" was not unlocking when adding first sake item
- Root cause: GamificationService.checkAndUnlockBadges() was never called in camera_screen.dart
## Changes
- Import gamification_service.dart
- Call checkAndUnlockBadges(ref) after adding sake item to Hive
- Display newly unlocked badges in success SnackBar
- Extend SnackBar duration when badges are unlocked (4s -> 6s)
## User Impact
- Users will now see badge unlock notifications: "バッジ獲得: 初めての一歩 🍶"
- All badge unlock conditions (first_step, regional, collector, flavor) now work correctly
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>
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