Add subdirectory routing mode for public domain deployments

Apps can now be served at domain.com/appname/ instead of requiring
subdomain DNS records (appname.domain.com). Supports three subpath
modes per template: native (URL base env var), strip (handle_path),
and none (incompatible warning). Tested on Linux with deploy/removal
lifecycle verified.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

status/js/core/grid.js

@@ -112,7 +112,7 @@
     }
   }
 
-  function serviceUrl(id) { return `https://${buildDomain(id)}`; }
+  function serviceUrl(id) { return buildServiceUrl(id); }
   function el(tag, cls, txt) { const n = document.createElement(tag); if (cls) n.className = cls; if (txt) n.textContent = txt; return n; }
 
   function buildGrid() {