Initial commit: MOPC platform with Docker deployment setup

Full Next.js 15 platform with tRPC, Prisma, PostgreSQL, NextAuth.
Includes production Dockerfile (multi-stage, port 7600), docker-compose
with registry-based image pull, Gitea Actions CI workflow, nginx config
for portal.monaco-opc.com, deployment scripts, and DEPLOYMENT.md guide.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/app/not-found.tsx

@@ -0,0 +1,18 @@
+import Link from 'next/link'
+import { Button } from '@/components/ui/button'
+import { FileQuestion } from 'lucide-react'
+
+export default function NotFound() {
+  return (
+    <div className="flex min-h-screen flex-col items-center justify-center gap-4 text-center">
+      <FileQuestion className="h-16 w-16 text-muted-foreground/50" />
+      <h1 className="text-2xl font-semibold">Page Not Found</h1>
+      <p className="text-muted-foreground">
+        The page you&apos;re looking for doesn&apos;t exist or has been moved.
+      </p>
+      <Button asChild>
+        <Link href="/">Go Home</Link>
+      </Button>
+    </div>
+  )
+}