Enable iCloud sync by default, remove user toggle

- CloudKit sync is now always enabled for all users
- Remove useCloudKit setting and toggle from Settings
- Remove CloudKitSyncMonitor usage (package can be removed)
- Remove container switching logic since sync is always on
- Update SharedModelContainer defaults to enable CloudKit

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Shared/Persisence/SharedModelContainer.swift

@@ -28,10 +28,10 @@ enum SharedModelContainer {
     private static let logger = Logger(subsystem: Bundle.main.bundleIdentifier ?? "com.tt.ifeel", category: "SharedModelContainer")
 
     /// Creates a ModelContainer with the appropriate configuration for app group sharing
-    /// - Parameter useCloudKit: Whether to enable CloudKit sync
+    /// - Parameter useCloudKit: Whether to enable CloudKit sync (defaults to true)
     /// - Returns: Configured ModelContainer
     /// - Throws: SharedModelContainerError if creation fails
-    static func create(useCloudKit: Bool = false) throws -> ModelContainer {
+    static func create(useCloudKit: Bool = true) throws -> ModelContainer {
         let schema = Schema([MoodEntryModel.self])
         let storeURL = try Self.storeURL
 
@@ -61,9 +61,9 @@ enum SharedModelContainer {
     }
 
     /// Creates a ModelContainer, falling back to in-memory storage if shared container fails
-    /// - Parameter useCloudKit: Whether to enable CloudKit sync
+    /// - Parameter useCloudKit: Whether to enable CloudKit sync (defaults to true)
     /// - Returns: Configured ModelContainer (shared or in-memory fallback)
-    static func createWithFallback(useCloudKit: Bool = false) -> ModelContainer {
+    static func createWithFallback(useCloudKit: Bool = true) -> ModelContainer {
         do {
             return try create(useCloudKit: useCloudKit)
         } catch {