refactor: flatten monorepo structure to backend/ frontend/ devops/

Rename subdirectories for a cleaner single-repo layout:
- website-monitoring-backend/  → backend/
- website-monitoring-frontend/ → frontend/
- website-monitoring-devops/   → devops/

Update all references in package.json scripts, CI workflows,
docker-compose, pre-commit hooks, and documentation.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

frontend/next.config.ts

@@ -0,0 +1,27 @@
+import type { NextConfig } from "next";
+
+const securityHeaders = [
+  { key: "X-DNS-Prefetch-Control", value: "on" },
+  { key: "Strict-Transport-Security", value: "max-age=63072000; includeSubDomains; preload" },
+  { key: "X-Frame-Options", value: "SAMEORIGIN" },
+  { key: "X-Content-Type-Options", value: "nosniff" },
+  { key: "Referrer-Policy", value: "origin-when-cross-origin" },
+  { key: "Permissions-Policy", value: "camera=(), microphone=(), geolocation=()" },
+];
+
+const nextConfig: NextConfig = {
+  eslint: {
+    // Do not fail production builds due to ESLint errors
+    ignoreDuringBuilds: true,
+  },
+  async headers() {
+    return [
+      {
+        source: "/(.*)",
+        headers: securityHeaders,
+      },
+    ];
+  },
+};
+
+export default nextConfig;