feat: add task comments feature with CRUD operations

- Introduced a new `task_comments` table in the database schema.
- Implemented task comments API endpoints for listing, creating, and deleting comments.
- Enhanced the task detail dialog to display comments and allow users to add new comments.
- Updated task row component to handle click events for viewing task details.
- Added a theme provider to manage light/dark mode across the application.
- Refactored Milkdown editor to use Crepe for improved markdown editing experience.
- Updated global styles to accommodate new editor and theme changes.
- Enhanced task filtering and sorting functionality in the tasks page.

src/renderer/components/ai/AIChatPanel.tsx

@@ -1,6 +1,36 @@
-import { Sparkles } from 'lucide-react';
+import { Sparkles, KeyRound } from 'lucide-react';
+import { trpc } from '@/lib/trpc';
+import { Card, CardContent } from '@/components/ui/card';
+import { Button } from '@/components/ui/button';
+
+interface AIChatPanelProps {
+  onOpenSettings?: () => void;
+}
+
+export function AIChatPanel({ onOpenSettings }: AIChatPanelProps) {
+  const hasTokenQuery = trpc.ai.hasToken.useQuery();
+
+  if (hasTokenQuery.data === false) {
+    return (
+      <div className="absolute inset-0 z-0 flex flex-col items-center justify-center bg-background">
+        <Card className="max-w-sm">
+          <CardContent className="flex flex-col items-center gap-4 pt-6">
+            <KeyRound size={32} className="text-muted-foreground" />
+            <div className="text-center space-y-1">
+              <p className="text-sm font-medium">AI provider not configured</p>
+              <p className="text-xs text-muted-foreground">
+                Connect your GitHub Copilot token to enable AI-powered features like chat, summaries, and suggestions.
+              </p>
+            </div>
+            <Button variant="outline" size="sm" onClick={onOpenSettings}>
+              Open Settings
+            </Button>
+          </CardContent>
+        </Card>
+      </div>
+    );
+  }
 
-export function AIChatPanel() {
   return (
     <div className="absolute inset-0 z-0 flex flex-col items-center justify-center bg-background">
       <Sparkles size={32} className="text-muted-foreground/40 mb-3" />