feat: implement full context-scoped AI chat UI in AIChatPanel

- Added AIChatPanel component with context header, user and AI message handling.
- Integrated streaming responses via IPC and error handling for chat mutations.
- Enhanced user experience with input handling and auto-scrolling features.
- Updated AppShell to derive AI chat context from the current route.
- Introduced ScrollArea component for better scrolling behavior in various dialogs.
- Added support for Tailwind typography and improved global styles.
- Updated project and task dialogs to utilize ScrollArea for better UX.

src/renderer/components/tasks/TaskDetailDialog.tsx

@@ -21,6 +21,7 @@ import { Badge } from '@/components/ui/badge';
 import { Button } from '@/components/ui/button';
 import { Separator } from '@/components/ui/separator';
 import { Input } from '@/components/ui/input';
+import { ScrollArea } from '@/components/ui/scroll-area';
 import { trpc } from '@/lib/trpc';
 import { PriorityBadge } from './PriorityBadge';
 import { parseAssignees, type TaskItem } from './TaskRow';
@@ -194,7 +195,8 @@ export function TaskDetailDialog({ task, open, onOpenChange, onEdit, onDelete }:
 
           <TabsContent value="comment" className="px-6 py-4 min-h-[120px] flex flex-col gap-4">
             {/* Comment list */}
-            <div className="flex flex-col gap-4 max-h-[260px] overflow-y-auto">
+            <ScrollArea className="max-h-[260px]">
+            <div className="flex flex-col gap-4">
               {(!comments || comments.length === 0) ? (
                 <p className="text-sm text-muted-foreground italic">No comments yet.</p>
               ) : (
@@ -223,6 +225,7 @@ export function TaskDetailDialog({ task, open, onOpenChange, onEdit, onDelete }:
                 ))
               )}
             </div>
+            </ScrollArea>
 
             {/* Add comment input */}
             <form