fix(infra): whitelist /_img proxy path and restore image config

- Whitelisted /_img path in Traefik labels to allow public access (fixing login page images)
- Restored dangerouslyAllowSVG and CSP settings in next.config.mjs (lost in shallow merge)
- Ensuring Next.js proxy works correctly behind Gatekeeper

next.config.mjs

@@ -319,6 +319,9 @@ const nextConfig = {
   images: {
     loader: 'custom',
     loaderFile: './lib/imgproxy-loader.ts',
+    dangerouslyAllowSVG: true,
+    contentDispositionType: "attachment",
+    contentSecurityPolicy: "default-src 'self'; script-src 'none'; sandbox;",
   },
   async rewrites() {
     const umamiUrl =