Fix Docker build and Next.js metadata configuration

- Move themeColor and viewport to separate viewport export in layout.tsx
- Improve Docker build process with npm ci and proper dependency handling
- Add Docker-friendly Next.js configuration settings
- Resolve constructor error and metadata warnings

app/layout.tsx

@@ -1,4 +1,4 @@
-import type { Metadata } from 'next'
+import type { Metadata, Viewport } from 'next'
 import './globals.css'
 import ServiceWorkerRegistration from '@/components/ServiceWorkerRegistration'
 import OfflineIndicator from '@/components/OfflineIndicator'
@@ -9,14 +9,6 @@ export const metadata: Metadata = {
   title: 'Ultimate Lists',
   description: 'The ultimate todo list app with advanced task management',
   manifest: '/manifest.json',
-  themeColor: '#3B82F6',
-  viewport: {
-    width: 'device-width',
-    initialScale: 1,
-    maximumScale: 1,
-    userScalable: false,
-    viewportFit: 'cover',
-  },
   appleWebApp: {
     capable: true,
     statusBarStyle: 'black-translucent',
@@ -39,6 +31,15 @@ export const metadata: Metadata = {
   },
 }
 
+export const viewport: Viewport = {
+  width: 'device-width',
+  initialScale: 1,
+  maximumScale: 1,
+  userScalable: false,
+  viewportFit: 'cover',
+  themeColor: '#3B82F6',
+}
+
 export default function RootLayout({
   children,
 }: {