feat: Kisani rebrand, step-based onboarding flow, dark mode fixes

- Rename app to Kisani in all UI text and Face ID prompt
- Replace flat 2-state RootView with 5-step flow: ConnectView →
  LoginView → FolderSetupView → PhotoPermissionView → MainTabView
- Remove NavigationStack from LoginView (was causing nested-stack crash);
  drive navigation via ConnectionStore.isSessionActive
- Add FolderSetupView and PhotoPermissionView onboarding screens with
  step indicator (2/3, 3/3), spring entrance animations, and UGreen
  connection chip
- Fix dark mode button invisibility: PrimaryButtonStyle and PillButtonStyle
  now use AppTheme.inkInverse; GhostButtonStyle border uses ink.opacity(0.25)
- Add AppTheme.inkInverse adaptive token (dark bg ink on dark, white on light)
- Add ConnectionStore.isSessionActive (non-persisted) and
  onboardingPhotoShown (UserDefaults-persisted)
- Add os_log logging in LoginViewModel at auth start/success/failure
- Remove dead Help button from ConnectView
- UGreenCompatibilityBadge, KeychainStore, SavedConnections, extensions,
  PrivacyInfo.xcprivacy, unit test target and test stubs
- AppTheme: full UIColor dynamic provider tokens for dark/light adaptive color
- AppearanceMode enum + segmented picker in SettingsView
- BackupView: enlarged ring, removed options card and linear progress bar
- HistoryView: duration and bytes formatting, improved typography hierarchy

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Shared/Persistence/SavedConnections.swift

@@ -0,0 +1,30 @@
+import Foundation
+
+// Bridges NASConnection save/load with Keychain for password and UserDefaults for metadata.
+enum SavedConnections {
+    private static let key = "savedConnection"
+
+    static func save(_ connection: NASConnection) {
+        KeychainStore.savePassword(connection.password, for: connection.id)
+        if let data = try? JSONEncoder().encode(connection) {
+            UserDefaults.standard.set(data, forKey: key)
+        }
+    }
+
+    static func load() -> NASConnection? {
+        guard let data = UserDefaults.standard.data(forKey: key),
+              var connection = try? JSONDecoder().decode(NASConnection.self, from: data) else {
+            return nil
+        }
+        connection.password = KeychainStore.loadPassword(for: connection.id) ?? ""
+        return connection
+    }
+
+    static func delete() {
+        if let data = UserDefaults.standard.data(forKey: key),
+           let connection = try? JSONDecoder().decode(NASConnection.self, from: data) {
+            KeychainStore.deletePassword(for: connection.id)
+        }
+        UserDefaults.standard.removeObject(forKey: key)
+    }
+}