fix: widgets use App Group shared UserDefaults instead of Keychain

- Widgets can't access app's Keychain (different sandbox)
- App writes data to shared UserDefaults (group.com.daniil.pulsehealth)
- Widgets read from shared UserDefaults — no API calls needed
- WidgetDataService: updates widget data + reloads timelines
- DashboardView: pushes habits/tasks data to widget after load
- HealthView: pushes health data to widget after load
- App Group capability added to both app and widget entitlements
- Widgets update every 15 minutes from cached data

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

PulseWidget/KeychainService.swift

@@ -1,49 +1,18 @@
 import Foundation
-import Security
 
-enum KeychainService {
-    static let service = "com.daniil.pulsehealth"
+// Widget reads data from shared UserDefaults (App Group), not Keychain
+enum WidgetData {
+    static let suiteName = "group.com.daniil.pulsehealth"
 
-    static func save(key: String, value: String) {
-        guard let data = value.data(using: .utf8) else { return }
-        let query: [String: Any] = [
-            kSecClass as String: kSecClassGenericPassword,
-            kSecAttrService as String: service,
-            kSecAttrAccount as String: key
-        ]
-        SecItemDelete(query as CFDictionary)
-        var add = query
-        add[kSecValueData as String] = data
-        add[kSecAttrAccessible as String] = kSecAttrAccessibleAfterFirstUnlock
-        SecItemAdd(add as CFDictionary, nil)
+    static var shared: UserDefaults? {
+        UserDefaults(suiteName: suiteName)
     }
 
-    static func load(key: String) -> String? {
-        let query: [String: Any] = [
-            kSecClass as String: kSecClassGenericPassword,
-            kSecAttrService as String: service,
-            kSecAttrAccount as String: key,
-            kSecReturnData as String: true,
-            kSecMatchLimit as String: kSecMatchLimitOne
-        ]
-        var result: AnyObject?
-        guard SecItemCopyMatching(query as CFDictionary, &result) == errSecSuccess,
-              let data = result as? Data else { return nil }
-        return String(data: data, encoding: .utf8)
-    }
-
-    static func delete(key: String) {
-        let query: [String: Any] = [
-            kSecClass as String: kSecClassGenericPassword,
-            kSecAttrService as String: service,
-            kSecAttrAccount as String: key
-        ]
-        SecItemDelete(query as CFDictionary)
-    }
-
-    // Keys
-    static let tokenKey = "auth_token"
-    static let refreshTokenKey = "auth_refresh_token"
-    static let healthTokenKey = "health_jwt_token"
-    static let healthApiKeyKey = "health_api_key"
+    static var habitsCompleted: Int { shared?.integer(forKey: "w_habits_completed") ?? 0 }
+    static var habitsTotal: Int { shared?.integer(forKey: "w_habits_total") ?? 0 }
+    static var tasksCount: Int { shared?.integer(forKey: "w_tasks_count") ?? 0 }
+    static var steps: Int { shared?.integer(forKey: "w_steps") ?? 0 }
+    static var sleep: Double { shared?.double(forKey: "w_sleep") ?? 0 }
+    static var heartRate: Int { shared?.integer(forKey: "w_heart_rate") ?? 0 }
+    static var readinessScore: Int { shared?.integer(forKey: "w_readiness") ?? 0 }
 }