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Removed outdated compatibility aliases and deprecated methods from AppColorScheme,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/asset/components/balance_card.dart

@@ -1,5 +1,5 @@
 import 'package:flutter/material.dart';
-import 'package:google_fonts/google_fonts.dart';
+import '../../../../core/theme/app_theme.dart';
 import '../../../../core/theme/app_color_scheme.dart';
 import '../../../../core/theme/app_spacing.dart';
 import '../../../../providers/asset_provider.dart';
@@ -37,28 +37,22 @@ class BalanceCard extends StatelessWidget {
         children: [
           Text(
             'USDT 余额',
-            style: GoogleFonts.inter(
-              fontSize: 12,
-              fontWeight: FontWeight.normal,
+            style: AppTextStyles.bodyMedium(context).copyWith(
               color: colorScheme.onSurfaceVariant,
+              fontWeight: FontWeight.w400,
             ),
           ),
           const SizedBox(height: 12),
           Text(
             _formatBalance(displayBalance),
-            style: GoogleFonts.inter(
-              fontSize: 28,
-              fontWeight: FontWeight.w700,
-              color: colorScheme.onSurface,
-            ),
+            style: AppTextStyles.numberLarge(context),
           ),
           const SizedBox(height: 12),
           Text(
             '\u2248 \$${_formatBalance(displayBalance)} USD',
-            style: GoogleFonts.inter(
-              fontSize: 12,
-              fontWeight: FontWeight.normal,
+            style: AppTextStyles.bodyMedium(context).copyWith(
               color: isDark ? AppColorScheme.darkOnSurfaceMuted : colorScheme.onSurfaceVariant,
+              fontWeight: FontWeight.w400,
             ),
           ),
         ],