Add PWA support and mobile optimizations

- Add manifest.json with PWA configuration
- Add viewport settings for iOS (viewport-fit: cover)
- Add meta tags for iOS Safari (apple-mobile-web-app-capable)
- Add mobile CSS optimizations:
  * iOS Safe Area support
  * Minimum 44x44px touch targets
  * Disable zoom on input focus
  * Remove scrollbars on mobile
  * Disable hover effects on touch devices
  * Standalone mode styles
- Add InstallPrompt component for Add to Home Screen
- Add SVG icon (needs PNG conversion)

frontend/src/app/(dashboard)/layout.tsx

@@ -5,6 +5,7 @@ import { useRouter, usePathname } from "next/navigation"
 import { useAuth } from "@/lib/auth"
 import { Loader2 } from "lucide-react"
 import { Sidebar } from "@/components/layout/Sidebar"
+import { InstallPrompt } from "@/components/ui/install-prompt"
 
 export default function DashboardLayout({
   children,
@@ -46,6 +47,7 @@ export default function DashboardLayout({
           {children}
         </div>
       </main>
+      <InstallPrompt />
     </div>
   )
 }