Refactor/shared appstorage

[mltbnz]

📝 Docs

• Did you update the CHANGELOG.md?

📲 What

This PR refactors the app's persistence layer by replacing the custom UserDefaultsClient dependency with TCA's native @Shared property wrapper and centralized SharedKey definitions.

Key Changes:

• Removed the UserDefaultsClient package entirely
• Added new SharedKeys package that defines all shared storage keys in one place
• Migrated all features to use @Shared property wrapper instead of dependency injection
• Consolidated storage configuration from multiple locations into a single source of truth

Migration Details:

AppStorage Keys (in-memory, fast access):

• chatReadTimeInterval - Double value for tracking chat read timestamp
• sessionID - Optional String for session identification
• didShowObservationModePrompt - Boolean flag

FileStorage Keys (JSON files, structured data):

• rideEventSettings - Event notification preferences
• appearanceSettings - Theme and UI preferences
• privacyZoneSettings - Location privacy configuration (includes migration from old location)

🤔 Why

Problems with the Old Approach:

1. Boilerplate overhead - Required defining client methods, live implementations, and test implementations for every storage operation
2. Scattered configuration - Storage keys were defined across multiple files (feature-specific SharedKey extensions)
3. Testing complexity - Required mocking the entire UserDefaultsClient dependency in tests
4. Less idiomatic - TCA now recommends @Shared for persistence over custom dependency clients

Benefits of the New Approach:

1. Less code - Eliminated ~100 lines of client/mock/test code
2. Centralized keys - All storage keys defined in one place (SharedKeys.swift)
3. Simpler usage - @Shared(.chatReadTimeInterval) var value instead of userDefaultsClient.chatReadTimeInterval
4. Better testing - @Shared automatically provides test isolation without mocking
5. Type safety - Storage keys are type-safe at compile time
6. Modern TCA pattern - Follows current TCA best practices from v1.9+

Code Comparison:

Before:

@Dependency(\.userDefaultsClient) var userDefaultsClient

return .run { _ in
  await userDefaultsClient.setChatReadTimeInterval(date().timeIntervalSince1970)
}

After:

@Shared(.chatReadTimeInterval) var chatReadTimeInterval
$chatReadTimeInterval.withLock { $0 = date().timeIntervalSince1970 }

👀 See

Files Changed:

• Removed: UserDefaultsClient package (3 files, ~100 lines)
• Added: SharedKeys package (2 files, ~80 lines)
• Updated: 6 feature modules to use @Shared
• Updated: Test files simplified (removed client mocking)

Package Structure:

CriticalMapsKit/
├── Sources/
│   ├── SharedKeys/          # NEW - centralized storage keys
│   │   ├── SharedKeys.swift
│   │   └── Export.swift
│   └── UserDefaultsClient/  # REMOVED
└── Tests/
    └── */                    # UPDATED - simplified mocking

Affected Features:

• ✅ AppFeature - session management
• ✅ ChatFeature - read timestamp tracking
• ✅ NextRideFeature - event settings
• ✅ SettingsFeature - appearance & privacy settings
• ✅ IDProvider - session ID persistence

♿️ Accessibility

• No UI changes - persistence layer refactor only
• All existing accessibility features maintained
• No impact on VoiceOver or Dynamic Type

🧪 Testing

• All tests updated and passing
• Test mocking simplified (removed UserDefaultsClient mocks)
• Privacy zone file migration tested
• Backward compatibility maintained for existing data

🔄 Migration Notes

This is a breaking change internally but not for end users:

• Existing UserDefaults values automatically migrate to @Shared storage
• Privacy zone files automatically migrate from Documents to Application Support directory
• No data loss - all existing user preferences preserved

---

Net Result: -109 lines of code, simpler architecture, better testability, more idiomatic TCA 🎉
closes #528