fix: update to latest @astrojs/starlight v0.37.5

Corrects previous commit that referenced non-existent v0.38.0.
The latest Starlight version is 0.37.5, which has peer dependency
astro@^5.5.0 that is compatible with Astro 5.16.x.

This update ensures we use the latest stable Starlight release
and may help resolve npm peer dependency warnings during installation.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

package.json

@@ -88,7 +88,7 @@
   },
   "devDependencies": {
     "@astrojs/sitemap": "^3.6.0",
-    "@astrojs/starlight": "^0.38.0",
+    "@astrojs/starlight": "^0.37.5",
     "@eslint/js": "^9.33.0",
     "archiver": "^7.0.1",
     "astro": "^5.16.0",