feat: Implement robust error/not-found pages & UI components

- Introduce dedicated error pages for dashboard and video routes
- Add specific not-found pages for dashboard, projects, videos, and settings
- Implement global `not-found.tsx` for general unhandled routes
- Integrate root and dashboard layouts with ErrorBoundary and Suspense
- Add new UI components: Accordion, Hover Card, Menubar, Navigation Menu, Select, Tabs
- Update Navbar to utilize the new Navigation Menu component
- Enhance `button` component with a `link` variant for better styling
- Refine existing UI components (dialog, dropdown, input, etc.)
- Update Tailwind config with new colors and animation extensions

app/api/upload/audio/[filename]/route.ts

@@ -1,6 +1,7 @@
 import { NextResponse } from 'next/server';
 import { r2Client, R2_BUCKET_NAME } from '@/lib/r2';
 import { GetObjectCommand } from '@aws-sdk/client-s3';
+import { apiErrors } from '@/lib/api-response';
 
 // Only allow UUID filenames with safe extensions
 const SAFE_FILENAME = /^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}\.[a-z0-9]+$/i;
@@ -14,7 +15,7 @@ export async function GET(
 
     // Validate filename to prevent path traversal
     if (!SAFE_FILENAME.test(filename)) {
-      return NextResponse.json({ error: 'Invalid filename' }, { status: 400 });
+      return apiErrors.badRequest('Invalid filename');
     }
 
     const key = `voice/${filename}`;
@@ -27,7 +28,7 @@ export async function GET(
     );
 
     if (!response.Body) {
-      return NextResponse.json({ error: 'File not found' }, { status: 404 });
+      return apiErrors.notFound('File');
     }
 
     const contentType = response.ContentType || 'audio/webm';
@@ -47,12 +48,9 @@ export async function GET(
   } catch (error: unknown) {
     const errorName = error instanceof Error ? error.name : '';
     if (errorName === 'NoSuchKey') {
-      return NextResponse.json({ error: 'File not found' }, { status: 404 });
+      return apiErrors.notFound('File');
     }
     console.error('Error serving audio:', error);
-    return NextResponse.json(
-      { error: 'Failed to retrieve audio' },
-      { status: 500 }
-    );
+    return apiErrors.internalError('Failed to retrieve audio');
   }
 }