feat: mobile long-press context menu, settings logout button

Mobile:
- Add useLongPress hook (500ms, movement cancellation, press feedback)
- Disable drag-and-drop on mobile in useEmailDrag
- Wire long-press context menu to all email list item components
- Add select-none and visual press feedback (scale + ring)

Settings:
- Add logout button to settings page sidebar

next.config.ts

@@ -3,6 +3,7 @@ import createNextIntlPlugin from "next-intl/plugin";
 
 const nextConfig: NextConfig = {
   output: "standalone",
+  allowedDevOrigins: ["192.168.1.51"],
   turbopack: {
     root: import.meta.dirname,
   },