Implement My Festival UI layer (Phase 4)

[Copilot]

Completes Phase 4 of the My Festival feature by implementing the UI layer on top of the existing data model and storage (Phases 1-3).

Changes

DrinkCard Status Badges

• Added visual status indicators overlaid at top-right corner
• Grey circle for "want to try", green checkmark for "tasted" with count badge (e.g., "2x")
• Uses FutureBuilder for async status loading, gracefully handles missing provider for tests

DrinkDetailScreen Tasting Tracker

• Replaced boolean "Tasted" checkbox with contextual button:
  • "Mark as Tasted" → "Tasted 2x" as user adds tastings
• Added "Tasting History" section listing timestamps with delete capability
• Extended repository interface with getTastingTimestamps() method
• Confirmation dialog prevents accidental deletion

FavoritesScreen → "My Festival" Log

• Unified view replacing old placeholder favorites screen
• Smart sort: "want to try" items first, then "tasted", alphabetical within groups
• Section dividers with labels separate groups
• Empty state guides users to build their log

Example Usage

// Status badge automatically appears on cards
DrinkCard(
  drink: drink,
  // _StatusBadge widget checks provider.getFavoriteStatus(drink)
  // Shows icon + count based on status and tryCount
)

// Detail screen shows full history
provider.getTastingTimestamps(drink)  // [DateTime1, DateTime2, ...]
provider.deleteTry(drink, timestamp)  // Remove specific tasting

All screens include Semantics labels per accessibility requirements. Analysis clean, 577/579 tests passing (2 pre-existing GoRouter test failures).

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