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/Theme/AppTheme.swift

@@ -1,55 +1,107 @@
 import SwiftUI
+import UIKit
+
+// MARK: — Appearance preference
+
+enum AppearanceMode: String, CaseIterable {
+    case system, light, dark
+
+    var resolvedScheme: ColorScheme? {
+        switch self {
+        case .system: return nil
+        case .light:  return .light
+        case .dark:   return .dark
+        }
+    }
+
+    var label: String {
+        switch self {
+        case .system: return "System"
+        case .light:  return "Light"
+        case .dark:   return "Dark"
+        }
+    }
+
+    var icon: String {
+        switch self {
+        case .system: return "circle.lefthalf.filled"
+        case .light:  return "sun.max"
+        case .dark:   return "moon"
+        }
+    }
+}
 
 enum AppTheme {
     // MARK: — Surfaces
-    static let background       = Color.white
-    static let surfaceRaised    = Color.white
-    static let surfaceSunken    = Color(hex: "#F5F5F5")
+    static let background    = Color(UIColor.systemBackground)
+    static let surfaceRaised = Color(UIColor.systemBackground)
+    static let surfaceSunken = Color(UIColor { t in
+        t.userInterfaceStyle == .dark
+            ? UIColor(white: 0.11, alpha: 1)
+            : UIColor(white: 0.961, alpha: 1)
+    })
 
     // MARK: — Ink
-    static let ink              = Color(hex: "#0F0F0F")
-    static let inkSecondary     = Color(hex: "#6B6B6B")
-    static let inkTertiary      = Color(hex: "#ABABAB")
-    static let inkQuaternary    = Color(hex: "#D4D4D4")
+    static let ink = Color(UIColor { t in
+        t.userInterfaceStyle == .dark
+            ? UIColor(white: 0.93, alpha: 1)
+            : UIColor(red: 0.059, green: 0.059, blue: 0.059, alpha: 1)
+    })
+    static let inkSecondary = Color(UIColor { t in
+        t.userInterfaceStyle == .dark
+            ? UIColor(white: 0.58, alpha: 1)
+            : UIColor(white: 0.42, alpha: 1)
+    })
+    static let inkTertiary = Color(UIColor { t in
+        t.userInterfaceStyle == .dark
+            ? UIColor(white: 0.40, alpha: 1)
+            : UIColor(white: 0.67, alpha: 1)
+    })
+    static let inkQuaternary = Color(UIColor { t in
+        t.userInterfaceStyle == .dark
+            ? UIColor(white: 0.22, alpha: 1)
+            : UIColor(white: 0.83, alpha: 1)
+    })
+
+    // Readable on AppTheme.ink background in both color schemes
+    static let inkInverse = Color(UIColor { t in
+        t.userInterfaceStyle == .dark
+            ? UIColor(red: 0.059, green: 0.059, blue: 0.059, alpha: 1)
+            : UIColor(white: 1.0, alpha: 1)
+    })
 
     // MARK: — Semantic
-    static let positive         = Color(hex: "#16A34A")
-    static let destructive      = Color(hex: "#DC2626")
-    static let interactive      = Color(hex: "#2563EB")
+    static let positive    = Color(hex: "#16A34A")
+    static let destructive = Color(hex: "#DC2626")
+    static let interactive = Color(hex: "#2563EB")
 
     // MARK: — Chrome
-    static let separator        = Color.black.opacity(0.07)
-    static let cardShadow       = Color.black.opacity(0.05)
-    static let cardBorderColor  = Color.black.opacity(0.07)
+    static let separator = Color(UIColor.separator)
+    static let cardShadow = Color(UIColor { t in
+        t.userInterfaceStyle == .dark
+            ? UIColor.clear
+            : UIColor.black.withAlphaComponent(0.048)
+    })
+    static let cardBorderColor = Color(UIColor.separator)
 
     // MARK: — Metrics
-    static let radius: CGFloat           = 14
-    static let radiusLarge: CGFloat      = 18
-    static let hPad: CGFloat             = 20
-    static let cardPad: CGFloat          = 16
-    static let sectionGap: CGFloat       = 28
+    static let radius: CGFloat      = 14
+    static let radiusLarge: CGFloat = 18
+    static let hPad: CGFloat        = 20
+    static let cardPad: CGFloat     = 16
+    static let sectionGap: CGFloat  = 28
 
     // MARK: — Typography
     static func display(_ size: CGFloat = 32) -> Font {
         .system(size: size, weight: .semibold, design: .default)
     }
-    static func title(_ size: CGFloat = 20) -> Font {
-        .system(size: size, weight: .semibold)
-    }
-    static func headline(_ size: CGFloat = 15) -> Font {
-        .system(size: size, weight: .medium)
-    }
-    static func body(_ size: CGFloat = 15) -> Font {
-        .system(size: size, weight: .regular)
-    }
-    static func caption(_ size: CGFloat = 13) -> Font {
-        .system(size: size, weight: .regular)
-    }
-    static func micro(_ size: CGFloat = 11) -> Font {
-        .system(size: size, weight: .medium)
-    }
+    static func title(_ size: CGFloat = 20) -> Font { .system(size: size, weight: .semibold) }
+    static func headline(_ size: CGFloat = 15) -> Font { .system(size: size, weight: .medium) }
+    static func body(_ size: CGFloat = 15) -> Font { .system(size: size, weight: .regular) }
+    static func caption(_ size: CGFloat = 13) -> Font { .system(size: size, weight: .regular) }
+    static func micro(_ size: CGFloat = 11) -> Font { .system(size: size, weight: .medium) }
 
-    // MARK: — Back-compat aliases used by existing call sites
+    // MARK: — Back-compat aliases
     static let blue             = interactive
     static let green            = positive
     static let red              = destructive
@@ -82,9 +134,7 @@ struct CardStyle: ViewModifier {
 }
 
 extension View {
-    func card(padded: Bool = true) -> some View {
-        modifier(CardStyle(padded: padded))
-    }
+    func card(padded: Bool = true) -> some View { modifier(CardStyle(padded: padded)) }
 
     @ViewBuilder func `if`<T: View>(_ condition: Bool, transform: (Self) -> T) -> some View {
         if condition { transform(self) } else { self }