build(deps-dev): bump the minor-and-patch group in /backend with 2 updates

Bumps the minor-and-patch group in /backend with 2 updates: [@biomejs/biome](https://github.com/biomejs/biome/tree/HEAD/packages/@biomejs/biome) and [@types/node](https://github.com/DefinitelyTyped/DefinitelyTyped/tree/HEAD/types/node).


Updates `@biomejs/biome` from 2.4.14 to 2.4.15
- [Release notes](https://github.com/biomejs/biome/releases)
- [Changelog](https://github.com/biomejs/biome/blob/main/packages/@biomejs/biome/CHANGELOG.md)
- [Commits](https://github.com/biomejs/biome/commits/@biomejs/biome@2.4.15/packages/@biomejs/biome)

Updates `@types/node` from 25.6.0 to 25.6.2
- [Release notes](https://github.com/DefinitelyTyped/DefinitelyTyped/releases)
- [Commits](https://github.com/DefinitelyTyped/DefinitelyTyped/commits/HEAD/types/node)

---
updated-dependencies:
- dependency-name: "@biomejs/biome"
  dependency-version: 2.4.15
  dependency-type: direct:development
  update-type: version-update:semver-patch
  dependency-group: minor-and-patch
- dependency-name: "@types/node"
  dependency-version: 25.6.2
  dependency-type: direct:development
  update-type: version-update:semver-patch
  dependency-group: minor-and-patch
...

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

backend/package.json

@@ -40,8 +40,8 @@
     "zod": "^4.4.3"
   },
   "devDependencies": {
-    "@biomejs/biome": "^2.4.14",
-    "@types/node": "^25.6.0",
+    "@biomejs/biome": "^2.4.15",
+    "@types/node": "^25.6.2",
     "@types/nodemailer": "^8.0.0",
     "@types/supertest": "^7.2.0",
     "@vitest/coverage-v8": "^4.1.5",