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/api/birdnet-api.php

@@ -216,6 +216,7 @@ switch ($action) {
             'quiet_end' => 6,
             'heal_hours' => 24,
             'timeout' => 45,
+            'frame_host' => '',
             'basic_user' => '',
             'basic_pass' => '',
         ];