build(deps): bump ai from 5.0.81 to 5.0.85

Bumps [ai](https://github.com/vercel/ai) from 5.0.81 to 5.0.85.
- [Release notes](https://github.com/vercel/ai/releases)
- [Changelog](https://github.com/vercel/ai/blob/main/CHANGELOG.md)
- [Commits](https://github.com/vercel/ai/compare/[email protected]@5.0.85)

---
updated-dependencies:
- dependency-name: ai
  dependency-version: 5.0.85
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

packages/backend/package.json

@@ -114,7 +114,7 @@
     "@ai-sdk/openai-compatible": "^1.0.24",
     "@huggingface/gguf": "^0.3.2",
     "@huggingface/hub": "^2.6.12",
-    "ai": "^5.0.81",
+    "ai": "^5.0.85",
     "express": "^5.1.0",
     "express-openapi-validator": "^5.6.0",
     "isomorphic-git": "^1.34.2",