chore(backend): bump @fastify/swagger-ui in /services/backend

Bumps [@fastify/swagger-ui](https://github.com/fastify/fastify-swagger-ui) from 5.2.6 to 6.0.0.
- [Release notes](https://github.com/fastify/fastify-swagger-ui/releases)
- [Commits](fastify/fastify-swagger-ui@v5.2.6...v6.0.0)

---
updated-dependencies:
- dependency-name: "@fastify/swagger-ui"
  dependency-version: 6.0.0
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

services/backend/package.json

@@ -26,7 +26,7 @@
     "@fastify/rate-limit": "^10.3.0",
     "@fastify/sse": "^0.4.0",
     "@fastify/swagger": "^9.7.0",
-    "@fastify/swagger-ui": "^5.2.5",
+    "@fastify/swagger-ui": "^6.0.0",
     "@lucia-auth/adapter-drizzle": "^1.1.0",
     "@modelcontextprotocol/sdk": "^1.27.1",
     "@node-rs/argon2": "^2.0.2",