rename: bridges/valves → tunnels (one term across types + API + UI)

API shape:
  GET /api/connections → GET /api/tunnels
  body: {"connections": […]} → {"tunnels": […]}

Type rename (package stays "bridge" — internal):
  Valve         → Listener
  clientBridge  → tunnel
  ConnSnapshot  → TunnelSnapshot

Log messages mirror the new vocab ("listener open/close", "tunnel
open/idle evict/forward failed"). UI header is now "Active tunnels"
and the empty state reads "no active tunnels".

server-manager's dashboard polls /infra/svc-proxy/api/tunnels and
shows "N tunnels" on the svc-proxy infra card.

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

internal/httpsrv/static/index.html

@@ -55,7 +55,7 @@
 </header>
 <main>
   <section>
-    <h2><span>Active connections <span class="count" id="conn-count"></span></span></h2>
+    <h2><span>Active tunnels <span class="count" id="conn-count"></span></span></h2>
     <table>
       <thead>
         <tr>
@@ -66,7 +66,7 @@
       </thead>
       <tbody id="conn-rows"></tbody>
     </table>
-    <div class="empty" id="conn-empty">no active bridges</div>
+    <div class="empty" id="conn-empty">no active tunnels</div>
   </section>
   <section>
     <h2><span>Logs</span><button onclick="document.getElementById('logbox').innerHTML=''">clear</button></h2>
@@ -88,20 +88,20 @@ const fmtAgo = secs => {
 };
 async function refreshConnections() {
   try {
-    const r = await fetch('./api/connections');
+    const r = await fetch('./api/tunnels');
     const j = await r.json();
     const rows = document.getElementById('conn-rows');
     const empty = document.getElementById('conn-empty');
     const count = document.getElementById('conn-count');
     rows.innerHTML = '';
     const now = new Date(j.at).getTime();
-    if (!j.connections || j.connections.length === 0) {
+    if (!j.tunnels || j.tunnels.length === 0) {
       empty.style.display = '';
       count.textContent = '';
     } else {
       empty.style.display = 'none';
-      count.textContent = '(' + j.connections.length + ')';
-      for (const c of j.connections) {
+      count.textContent = '(' + j.tunnels.length + ')';
+      for (const c of j.tunnels) {
         const opened = new Date(c.opened_at).getTime();
         const ageSecs = (now - opened) / 1000;
         const idleCls = c.idle_seconds > 60 ? 'dead' : c.idle_seconds > 30 ? 'stale' : '';
@@ -118,7 +118,7 @@ async function refreshConnections() {
         rows.appendChild(tr);
       }
     }
-    document.getElementById('meta').textContent = '— ' + j.connections.length + ' bridges';
+    document.getElementById('meta').textContent = '— ' + j.tunnels.length + ' tunnels';
   } catch (e) {
     document.getElementById('meta').textContent = '— api error';
   }