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>

Tests/MockNASService.swift

@@ -0,0 +1,49 @@
+import Foundation
+@testable import NASBackup
+
+final class MockNASService: NASTransferProtocol {
+    var shouldFail: Bool = false
+    var uploadDelay: TimeInterval = 0
+    var fakeItems: [NASItem] = []
+    var fileExistsAnswer: Bool = false
+
+    private(set) var connectCalled = false
+    private(set) var uploadCallCount = 0
+    private(set) var lastUploadedPath: String?
+
+    var isConnected: Bool = false
+
+    func connect(to host: String, port: Int, username: String, password: String) async throws {
+        connectCalled = true
+        if shouldFail { throw MockError.connectionFailed }
+        isConnected = true
+    }
+
+    func disconnect() { isConnected = false }
+
+    func listDirectory(at path: String) async throws -> [NASItem] {
+        if shouldFail { throw MockError.connectionFailed }
+        return fakeItems
+    }
+
+    func createDirectory(at path: String) async throws {
+        if shouldFail { throw MockError.connectionFailed }
+    }
+
+    func fileExists(at remotePath: String) async throws -> Bool { fileExistsAnswer }
+
+    func upload(localURL: URL, remotePath: String, progress: @escaping (Int64, Int64) -> Void) async throws {
+        if uploadDelay > 0 {
+            try await Task.sleep(nanoseconds: UInt64(uploadDelay * 1_000_000_000))
+        }
+        if shouldFail { throw MockError.uploadFailed }
+        progress(100, 100)
+        uploadCallCount += 1
+        lastUploadedPath = remotePath
+    }
+}
+
+enum MockError: Error {
+    case connectionFailed
+    case uploadFailed
+}