docs(theme): update documentation and clean up deprecated color scheme definitions

Removed outdated compatibility aliases and deprecated methods from AppColorScheme,
and updated CLAUDE.md to reflect new theme system requirements with centralized
color management and no hard-coded values in UI components.

flutter_monisuo/lib/ui/pages/auth/login_page.dart

@@ -4,6 +4,7 @@ import 'package:provider/provider.dart';
 
 import '../../../core/theme/app_color_scheme.dart';
 import '../../../core/theme/app_spacing.dart';
+import '../../../core/theme/app_theme.dart';
 import '../../../providers/auth_provider.dart';
 import '../main/main_page.dart';
 import 'register_page.dart';
@@ -26,9 +27,6 @@ class _LoginPageState extends State<LoginPage> {
   static const _inputHeight = 52.0;
   static const _buttonHeight = 52.0;
 
-  /// 设计稿 radius-lg = 14
-  static const _designRadiusLg = 14.0;
-
   @override
   void dispose() {
     _usernameController.dispose();
@@ -86,18 +84,18 @@ class _LoginPageState extends State<LoginPage> {
             gradient: const LinearGradient(
               begin: Alignment.topCenter,
               end: Alignment.bottomCenter,
-              colors: [Color(0xFF1F2937), Color(0xFF374151)],
+              colors: [AppColorScheme.darkSurfaceContainerHigh, AppColorScheme.darkOutline],
             ),
           ),
           alignment: Alignment.center,
           child: Text(
             'M',
-            style: TextStyle(
+            style: AppTextStyles.displayLarge(context).copyWith(
               fontSize: 32,
               fontWeight: FontWeight.w800,
               color: isDark
                   ? AppColorScheme.darkOnSurface
-                  : Colors.white,
+                  : AppColorScheme.darkOnPrimary,
             ),
           ),
         ),
@@ -105,9 +103,7 @@ class _LoginPageState extends State<LoginPage> {
         // 品牌名 "MONISUO"
         Text(
           'MONISUO',
-          style: TextStyle(
-            fontSize: 28,
-            fontWeight: FontWeight.w800,
+          style: AppTextStyles.displayLarge(context).copyWith(
             letterSpacing: 3,
             color: isDark
                 ? AppColorScheme.darkOnSurface
@@ -119,9 +115,7 @@ class _LoginPageState extends State<LoginPage> {
         // 标语
         Text(
           '虚拟货币模拟交易平台',
-          style: TextStyle(
-            fontSize: 13,
-            fontWeight: FontWeight.normal,
+          style: AppTextStyles.bodyLarge(context).copyWith(
             color: isDark
                 ? AppColorScheme.darkOnSurfaceVariant
                 : AppColorScheme.lightOnSurfaceVariant,
@@ -174,11 +168,10 @@ class _LoginPageState extends State<LoginPage> {
         decoration: ShadDecoration(
           border: ShadBorder.all(
             color: borderColor,
-            radius: BorderRadius.circular(_designRadiusLg),
+            radius: AppRadius.radiusLg,
           ),
         ),
-        style: TextStyle(
-          fontSize: 14,
+        style: AppTextStyles.headlineMedium(context).copyWith(
           color: isDark
               ? AppColorScheme.darkOnSurface
               : AppColorScheme.lightOnSurface,
@@ -218,11 +211,10 @@ class _LoginPageState extends State<LoginPage> {
         decoration: ShadDecoration(
           border: ShadBorder.all(
             color: borderColor,
-            radius: BorderRadius.circular(_designRadiusLg),
+            radius: AppRadius.radiusLg,
           ),
         ),
-        style: TextStyle(
-          fontSize: 14,
+        style: AppTextStyles.headlineMedium(context).copyWith(
           color: isDark
               ? AppColorScheme.darkOnSurface
               : AppColorScheme.lightOnSurface,
@@ -235,10 +227,10 @@ class _LoginPageState extends State<LoginPage> {
     // 设计稿: accent-primary = light:#1F2937 / dark:#D4AF37
     final buttonColor = isDark
         ? AppColorScheme.darkSecondary
-        : const Color(0xFF1F2937);
+        : AppColorScheme.darkSurfaceContainerHigh;
     final textColor = isDark
         ? AppColorScheme.darkBackground
-        : Colors.white;
+        : AppColorScheme.darkOnPrimary;
 
     return Consumer<AuthProvider>(
       builder: (context, auth, _) {
@@ -250,7 +242,7 @@ class _LoginPageState extends State<LoginPage> {
             foregroundColor: textColor,
             decoration: ShadDecoration(
               border: ShadBorder.all(
-                radius: BorderRadius.circular(_designRadiusLg),
+                radius: AppRadius.radiusLg,
               ),
             ),
             child: auth.isLoading
@@ -263,8 +255,7 @@ class _LoginPageState extends State<LoginPage> {
                   )
                 : Text(
                     '登录',
-                    style: TextStyle(
-                      fontSize: 16,
+                    style: AppTextStyles.headlineLarge(context).copyWith(
                       fontWeight: FontWeight.w700,
                       color: textColor,
                     ),
@@ -283,7 +274,7 @@ class _LoginPageState extends State<LoginPage> {
     // gold-accent: light=#F59E0B / dark=#D4AF37
     final goldColor = isDark
         ? AppColorScheme.darkSecondary
-        : const Color(0xFFF59E0B);
+        : AppColorScheme.darkSecondaryFixed;
     final secondaryTextColor = isDark
         ? AppColorScheme.darkOnSurfaceVariant
         : AppColorScheme.lightOnSurfaceVariant;
@@ -295,9 +286,7 @@ class _LoginPageState extends State<LoginPage> {
         children: [
           Text(
             '还没有账户？',
-            style: TextStyle(
-              fontSize: 13,
-              fontWeight: FontWeight.normal,
+            style: AppTextStyles.bodyLarge(context).copyWith(
               color: secondaryTextColor,
             ),
           ),
@@ -306,8 +295,7 @@ class _LoginPageState extends State<LoginPage> {
             onTap: _navigateToRegister,
             child: Text(
               '立即注册',
-              style: TextStyle(
-                fontSize: 13,
+              style: AppTextStyles.bodyLarge(context).copyWith(
                 fontWeight: FontWeight.w600,
                 color: goldColor,
               ),