refactor(apps): 主题系统迁移至 ColorScheme + 扩展架构并支持 Dark Mode

apps/lib/features/home/presentation/widgets/home_attachment_strip.dart

@@ -24,13 +24,15 @@ class HomeAttachmentStrip extends StatelessWidget {
       return const SizedBox.shrink();
     }
 
+    final colorScheme = Theme.of(context).colorScheme;
+
     return Container(
       key: homeAttachmentStripKey,
       padding: const EdgeInsets.all(AppSpacing.sm),
       decoration: BoxDecoration(
-        color: AppColors.homeAttachmentSurface,
+        color: colorScheme.surfaceContainerLow,
         borderRadius: BorderRadius.circular(AppRadius.xl),
-        border: Border.all(color: AppColors.homeComposerBorder),
+        border: Border.all(color: colorScheme.outlineVariant),
       ),
       child: Wrap(
         spacing: AppSpacing.sm,
@@ -55,6 +57,7 @@ class _AttachmentPreviewTile extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     const previewExtent = AppSpacing.xxl * 3 + AppSpacing.sm;
+    final colorScheme = Theme.of(context).colorScheme;
 
     return Stack(
       children: [
@@ -69,12 +72,12 @@ class _AttachmentPreviewTile extends StatelessWidget {
               return Container(
                 width: previewExtent,
                 height: previewExtent,
-                color: AppColors.white,
+                color: colorScheme.surface,
                 alignment: Alignment.center,
-                child: const Icon(
+                child: Icon(
                   LucideIcons.image,
                   size: AppSpacing.xl,
-                  color: AppColors.slate400,
+                  color: colorScheme.onSurfaceVariant,
                 ),
               );
             },
@@ -88,14 +91,14 @@ class _AttachmentPreviewTile extends StatelessWidget {
             child: Container(
               width: AppSpacing.lg + AppSpacing.sm,
               height: AppSpacing.lg + AppSpacing.sm,
-              decoration: const BoxDecoration(
-                color: AppColors.red500,
+              decoration: BoxDecoration(
+                color: colorScheme.error,
                 shape: BoxShape.circle,
               ),
-              child: const Icon(
+              child: Icon(
                 LucideIcons.x,
                 size: AppSpacing.md,
-                color: AppColors.white,
+                color: colorScheme.onError,
               ),
             ),
           ),