build(deps-dev): bump @types/node from 22.19.3 to 25.2.3 in /backend (#191)

Bumps [@types/node](https://github.com/DefinitelyTyped/DefinitelyTyped/tree/HEAD/types/node) from 22.19.3 to 25.2.3.
- [Release notes](https://github.com/DefinitelyTyped/DefinitelyTyped/releases)
- [Commits](https://github.com/DefinitelyTyped/DefinitelyTyped/commits/HEAD/types/node)

---
updated-dependencies:
- dependency-name: "@types/node"
  dependency-version: 25.2.3
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

backend/package.json

@@ -36,7 +36,7 @@
   },
   "devDependencies": {
     "@biomejs/biome": "^2.3.15",
-    "@types/node": "^22.7.4",
+    "@types/node": "^25.2.3",
     "@types/nodemailer": "^6.4.21",
     "@types/supertest": "^6.0.2",
     "@vitest/coverage-v8": "^4.0.18",