docs: upgrade docs site to Astro 6 and update Node.js prerequisites (#244)

Upgrades the docs site from Astro 5/Starlight 0.37 to Astro 6/Starlight 0.38.
Adds Cloudflare adapter for deployment. Updates Node.js prerequisites
across all docs to match Astro 6's requirement of v22.12.0+.
Bumps catalog versions for @astrojs/cloudflare and wrangler.

docs/astro.config.mjs

@@ -1,3 +1,4 @@
+import cloudflare from "@astrojs/cloudflare";
 import starlight from "@astrojs/starlight";
 // @ts-check
 import { defineConfig } from "astro/config";
@@ -162,4 +163,6 @@ export default defineConfig({
 			],
 		}),
 	],
+
+	adapter: cloudflare(),
 });