Bump astro from 5.14.5 to 5.15.4 in /client

Bumps [astro](https://github.com/withastro/astro/tree/HEAD/packages/astro) from 5.14.5 to 5.15.4.
- [Release notes](https://github.com/withastro/astro/releases)
- [Changelog](https://github.com/withastro/astro/blob/main/packages/astro/CHANGELOG.md)
- [Commits](https://github.com/withastro/astro/commits/[email protected]/packages/astro)

---
updated-dependencies:
- dependency-name: astro
  dependency-version: 5.15.4
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

client/package-lock.json

@@ -14,7 +14,7 @@
     "@astrojs/node": "^9.4.6",
     "@astrojs/svelte": "^7.2.1",
     "@tailwindcss/vite": "^4.1.16",
-    "astro": "^5.12.3",
+    "astro": "^5.15.5",
     "svelte": "^5.43.5",
     "typescript": "^5.9.3"
   },