Introduce unified design tokens and migrate Home, Orders, and Statistics UI.

Establish AppColor/AppFont/AppSpacing/AppRadius theming, shared components, and design-system docs so pilot screens align with Android while keeping iOS-native spacing and touch targets.

Co-authored-by: Cursor <cursoragent@cursor.com>

suixinkan/UI/Common/AppButton.swift

@@ -32,14 +32,14 @@ final class AppButton: UIButton {
     }
 
     private func setupUI(title: String) {
-        titleLabel?.font = .systemFont(ofSize: 14, weight: .regular)
-        layer.cornerRadius = 10
+        titleLabel?.font = .app(.body)
+        layer.cornerRadius = AppRadius.md
         clipsToBounds = true
         setTitle(title, for: .normal)
         updateAppearance()
 
         snp.makeConstraints { make in
-            make.height.equalTo(46)
+            make.height.equalTo(AppSpacing.buttonHeight)
         }
     }