feat(health): pure helper to pick local/remote service URLs

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

public/views/service_url.js

@@ -0,0 +1,28 @@
+// Pure helpers: choose which URL a service tile opens, based on whether the dashboard
+// is being viewed on-network (LAN) or remotely. No DOM / no network access here.
+
+const PRIVATE_RE = /^(localhost$|127\.|10\.|192\.168\.|172\.(1[6-9]|2\d|3[01])\.)/;
+
+// True when `hostname` is NOT a private/local address — i.e. the dashboard is being
+// accessed remotely (e.g. via void.hynesy.com).
+export function isRemoteHost(hostname = '') {
+  const h = String(hostname).toLowerCase();
+  if (!h) return false;
+  if (PRIVATE_RE.test(h)) return false;
+  if (h.endsWith('.local') || h.endsWith('.lan')) return false;
+  if (!h.includes('.')) return false;            // bare hostname (e.g. "ct311")
+  return true;
+}
+
+// For a service ({ url, external }) and whether we're remote, return the primary URL
+// the tile opens, an optional alt (the other URL) for one-click fallback, and whether
+// the service is LAN-only while remote.
+export function pickServiceUrls(svc = {}, remote = false) {
+  const url = svc.url || '';
+  const external = svc.external || '';
+  let primary, alt;
+  if (remote) { primary = external || url; alt = external ? url : ''; }
+  else        { primary = url;             alt = external || ''; }
+  if (alt && alt === primary) alt = '';
+  return { primary, alt: alt || null, lanOnly: remote && !external };
+}