feat(frontend): Implement Phase 2 - Complete Projects UI with CRUD operations

Implemented comprehensive Projects UI with full CRUD functionality following
modern React best practices and using shadcn/ui components.

Changes:
- Created ProjectForm component with react-hook-form + zod validation
  - Auto-uppercase project key input
  - Comprehensive field validation (name, key, description)
  - Support for both create and edit modes
  - Toast notifications for success/error states

- Enhanced Projects List Page (app/(dashboard)/projects/page.tsx)
  - Beautiful card-based grid layout with hover effects
  - Skeleton loading states for better UX
  - Empty state with call-to-action
  - Project metadata display (key badge, created date)
  - Integrated ProjectForm in Dialog for creation

- Enhanced Project Detail Page (app/(dashboard)/projects/[id]/page.tsx)
  - Comprehensive project information display
  - Edit functionality with dialog form
  - Delete functionality with confirmation AlertDialog
  - Epics preview section with stats
  - Quick actions sidebar (Kanban, Epics)
  - Statistics card (Total/Active/Completed epics)
  - Skeleton loading states
  - Error handling with retry capability

- Added toast notifications (Sonner)
  - Installed and configured sonner package
  - Added Toaster component to root layout
  - Success/error notifications for all CRUD operations

- Installed required dependencies
  - date-fns for date formatting
  - sonner for toast notifications
  - shadcn/ui alert-dialog component

Technical highlights:
- TypeScript with strict type checking
- React Query for data fetching and caching
- Optimistic updates with automatic rollback
- Responsive design (mobile-friendly)
- Accessibility-focused components
- Clean error handling throughout

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

app/(auth)/login/page.tsx

@@ -13,6 +13,7 @@ import { useSearchParams } from 'next/navigation';
 const loginSchema = z.object({
   email: z.string().email('Invalid email address'),
   password: z.string().min(8, 'Password must be at least 8 characters'),
+  tenantSlug: z.string().min(1, 'Tenant slug is required'),
 });
 
 type LoginForm = z.infer<typeof loginSchema>;
@@ -60,6 +61,20 @@ export default function LoginPage() {
             </div>
           )}
 
+          <div>
+            <Label htmlFor="tenantSlug">Tenant Slug</Label>
+            <Input
+              id="tenantSlug"
+              type="text"
+              {...register('tenantSlug')}
+              className="mt-1"
+              placeholder="your-company"
+            />
+            {errors.tenantSlug && (
+              <p className="mt-1 text-sm text-red-600">{errors.tenantSlug.message}</p>
+            )}
+          </div>
+
           <div>
             <Label htmlFor="email">Email</Label>
             <Input