2.0: CloudKit private-database sync replaces KV snapshot sync

Foundation for 2.1 family sharing (CKShare needs these models + container).
SwiftData cannot share across Apple IDs today, so 2.0 ships true multi-device
sync for the same account instead:

- Models made CloudKit-compatible: dropped @Attribute(.unique) on all 5,
  inline defaults on every attribute, WeekPlan.slots stored as optional
  relationship (name preserved → lightweight migration) with non-optional
  slotList facade; ~73 call sites renamed.
- Container: cloudKitDatabase .automatic, falling back to the local-only
  store when CloudKit is unavailable; failures recorded to Crashlytics.
- Entitlements: iCloud CloudKit service (container already existed);
  remote-notification background mode for push-driven sync.
- Legacy KV snapshot sync (ICloudSyncService) stays inert when CloudKit is
  active — kept only for 1.x devices.
- DeduplicationService collapses cross-device duplicates deterministically on
  launch (settings singleton, default tags with tagId remapping, same-week
  plans).
- Note: AppSettings.isPremium now syncs across same-Apple-ID devices; StoreKit
  (PremiumSyncService + Transaction.updates) remains the source of truth and
  reconciles on every launch/foreground.

All 21 unit tests pass, including ICloudSyncPremiumIsolationTests.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BkanrydYtrme8wipTzWssG

MealMood/Resources/MealMood.entitlements

@@ -6,6 +6,10 @@
 	<array>
 		<string>iCloud.com.alexandrev.mealmood</string>
 	</array>
+	<key>com.apple.developer.icloud-services</key>
+	<array>
+		<string>CloudKit</string>
+	</array>
 	<key>com.apple.developer.ubiquity-kvstore-identifier</key>
 	<string>$(TeamIdentifierPrefix)$(CFBundleIdentifier)</string>
 	<key>com.apple.security.application-groups</key>