Bump astro from 5.9.1 to 5.12.3 in /client

Bumps [astro](https://github.com/withastro/astro/tree/HEAD/packages/astro) from 5.9.1 to 5.12.3.
- [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: 5.12.3
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

client/package-lock.json

@@ -13,7 +13,7 @@
     "@astrojs/node": "^9.2.2",
     "@astrojs/svelte": "^7.1.0",
     "@tailwindcss/vite": "^4.1.11",
-    "astro": "^5.9.1",
+    "astro": "^5.12.3",
     "svelte": "^5.33.12",
     "typescript": "^5.8.3"
   },