Adopt root-level tsswift app layout

Move the app payload under swift/ while keeping git, package.json, and .smartconfig.json at the repo root. This standardizes the Swift app setup so build, test, run, and watch workflows match the other repos.

swift/Sources/Core/Services/AppStateStore.swift

@@ -0,0 +1,46 @@
+import Foundation
+
+struct PersistedAppState: Codable, Equatable {
+    let session: AuthSession
+    let profile: MemberProfile
+    let requests: [ApprovalRequest]
+    let notifications: [AppNotification]
+}
+
+protocol AppStateStoring {
+    func load() -> PersistedAppState?
+    func save(_ state: PersistedAppState)
+    func clear()
+}
+
+final class UserDefaultsAppStateStore: AppStateStoring {
+    private let defaults: UserDefaults
+    private let storageKey: String
+    private let encoder = JSONEncoder()
+    private let decoder = JSONDecoder()
+
+    init(defaults: UserDefaults = .standard, storageKey: String = "persisted-app-state") {
+        self.defaults = defaults
+        self.storageKey = storageKey
+    }
+
+    func load() -> PersistedAppState? {
+        guard let data = defaults.data(forKey: storageKey) else {
+            return nil
+        }
+
+        return try? decoder.decode(PersistedAppState.self, from: data)
+    }
+
+    func save(_ state: PersistedAppState) {
+        guard let data = try? encoder.encode(state) else {
+            return
+        }
+
+        defaults.set(data, forKey: storageKey)
+    }
+
+    func clear() {
+        defaults.removeObject(forKey: storageKey)
+    }
+}