feat!: implement redirect for hosting base domain

Redirect the subdomains `""` and `"www"` to a configurable URL, which is
by default `https://developer.puter.com/static-hosting/`.

This is potentially a breaking change for local instances that have a
subdomain called "www". Users hosting their own Puter may want to be
aware of this.

Closes #2214

src/backend/src/config.js

@@ -67,6 +67,7 @@ config.monitor = {
 config.max_subdomains_per_user = 2000;
 config.storage_capacity = 1 * 1024 * 1024 * 1024;
 config.static_hosting_domain = 'site.puter.localhost';
+config.static_hosting_base_domain_redirect = 'https://developer.puter.com/static-hosting/';
 
 // Storage limiting is set to false by default
 // Storage available on the mountpoint/drive puter is running is the storage available

src/backend/src/routers/hosting/puter-site.js

@@ -116,6 +116,11 @@ class PuterSiteMiddleware extends AdvancedBase {
             };
         });
 
+        if ( subdomain === '' || subdomain === 'www' ) {
+            // redirect to information page about static hosting
+            return res.redirect(config.static_hosting_base_domain_redirect);
+        }
+
         const site =
             await get_username_site() ||
             await (async () => {