Migrate from Core Data to SwiftData

- Replace Core Data with SwiftData for iOS 18+
- Create MoodEntryModel as @Model class replacing MoodEntry entity
- Create SharedModelContainer for App Group container sharing
- Create DataController with CRUD extensions replacing PersistenceController
- Update all views and view models to use MoodEntryModel
- Update widget extension to use SwiftData
- Remove old Core Data files (Persistence*.swift, .xcdatamodeld)
- Add EntryType enum with all entry type cases
- Fix widget label truncation with proper spacing and text scaling

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

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

Shared/Persisence/DataController.swift

@@ -0,0 +1,82 @@
+//
+//  DataController.swift
+//  Feels
+//
+//  SwiftData controller replacing Core Data PersistenceController.
+//
+
+import SwiftData
+import SwiftUI
+
+@MainActor
+final class DataController: ObservableObject {
+    static let shared = DataController()
+
+    private(set) var container: ModelContainer
+
+    var modelContext: ModelContext {
+        container.mainContext
+    }
+
+    private var useCloudKit: Bool {
+        GroupUserDefaults.groupDefaults.bool(forKey: UserDefaultsStore.Keys.useCloudKit.rawValue)
+    }
+
+    // Listeners for data changes (keeping existing pattern)
+    var switchContainerListeners = [(() -> Void)]()
+    private var editedDataClosure = [() -> Void]()
+
+    // Computed properties for earliest/latest entries
+    var earliestEntry: MoodEntryModel? {
+        var descriptor = FetchDescriptor<MoodEntryModel>(
+            sortBy: [SortDescriptor(\.forDate, order: .forward)]
+        )
+        descriptor.fetchLimit = 1
+        return try? modelContext.fetch(descriptor).first
+    }
+
+    var latestEntry: MoodEntryModel? {
+        var descriptor = FetchDescriptor<MoodEntryModel>(
+            sortBy: [SortDescriptor(\.forDate, order: .reverse)]
+        )
+        descriptor.fetchLimit = 1
+        return try? modelContext.fetch(descriptor).first
+    }
+
+    private init() {
+        let cloudKit = GroupUserDefaults.groupDefaults.bool(forKey: UserDefaultsStore.Keys.useCloudKit.rawValue)
+        container = SharedModelContainer.create(useCloudKit: cloudKit)
+    }
+
+    // MARK: - Container Switching (for CloudKit toggle)
+
+    func switchContainer() {
+        save()
+        container = SharedModelContainer.create(useCloudKit: useCloudKit)
+        for listener in switchContainerListeners {
+            listener()
+        }
+    }
+
+    // MARK: - Listener Management
+
+    func addNewDataListener(closure: @escaping (() -> Void)) {
+        editedDataClosure.append(closure)
+    }
+
+    func saveAndRunDataListeners() {
+        save()
+        for closure in editedDataClosure {
+            closure()
+        }
+    }
+
+    func save() {
+        guard modelContext.hasChanges else { return }
+        do {
+            try modelContext.save()
+        } catch {
+            print("Failed to save context: \(error)")
+        }
+    }
+}