automc ui: relative api paths so /infra/mc-router/ proxying works

Same fix as svc-proxy: absolute /api/* hit the server-manager origin
when the UI is reverse-proxied at /infra/mc-router/. Switch to ./api/*
so the requests stay under the proxied prefix.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

internal/automc/static/index.html

@@ -92,7 +92,7 @@
 <script>
 async function refreshRoutes() {
   try {
-    const r = await fetch('/api/routes');
+    const r = await fetch('./api/routes');
     const j = await r.json();
     const rows = document.getElementById('route-rows');
     const empty = document.getElementById('route-empty');
@@ -121,7 +121,7 @@ refreshRoutes();
 function startLogStream() {
   const status = document.getElementById('status');
   const box = document.getElementById('logbox');
-  const es = new EventSource('/api/logs');
+  const es = new EventSource('./api/logs');
   es.onopen = () => { status.textContent = 'log stream: live'; status.className = 'status ok'; };
   es.onerror = () => { status.textContent = 'log stream: reconnecting'; status.className = 'status err'; };
   es.onmessage = ev => {