Add Refresh Now button and configurable frame_host

- Trigger endpoint on frame Pi (port 8080) starts birdframe.service
- Frame admin panel has a Refresh Now button at the top
- frame_host config field lets user set the frame Pi's IP/hostname
- Button uses frame_host from config (no hardcoded hostname)

Co-Authored-By: Claude Opus 4 <noreply@anthropic.com>

avian/frontend/styles.css

@@ -1634,3 +1634,17 @@ body.av-local #dd-items  { display: block; }
   }
   .frame-section-label:first-child { padding-top: 4px; }
 
+
+  .frame-refresh-btn {
+    font: 600 13px/1 var(--sans, ui-sans-serif, system-ui, sans-serif);
+    padding: 10px 24px;
+    border: 1px solid var(--ink-soft, #8a8078);
+    border-radius: 6px;
+    background: transparent;
+    color: var(--ink, #1a1612);
+    cursor: pointer;
+    transition: background 0.15s, opacity 0.15s;
+  }
+  .frame-refresh-btn:hover { background: rgba(26,22,18,0.05); }
+  .frame-refresh-btn:disabled { opacity: 0.5; cursor: default; }
+