Add Frame admin panel with full remote config

- New frame_config API endpoint (GET/POST) stores all frame display
  settings in frame-config.json on the BirdNET server
- Frame menu item in the admin drawer opens a full settings panel
  with sections: Display, Titles, Collage, Hardware, Source, Auth
- Changes auto-save via debounced POST; the frame Pi picks them up
  on its next 15-min timer cycle
- TODAY window button in the time picker with configurable start
  hour (localStorage bird:todayStart, adjustable in Settings)

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

avian/api/birdnet-api.php

@@ -184,6 +184,64 @@ switch ($action) {
         break;
     }
 
+
+    case 'frame_config': {
+        $cfg_path = __DIR__ . '/frame-config.json';
+        $defaults = [
+            'mode' => 'today',
+            'hours' => 24,
+            'start_time' => '06:00',
+            'hold_overnight' => true,
+            'species_source' => '',
+            'zip' => '',
+            'bw_days' => 7,
+            'bw_country' => 'us',
+            'image_url' => '',
+            'shoot' => true,
+            'shoot_title' => 'avian visitors',
+            'shoot_subtitle' => 'Heard Today',
+            'shoot_headline_px' => 42,
+            'shoot_eyebrow_px' => 18,
+            'shoot_lowercase' => false,
+            'shoot_mat' => 0.04,
+            'shoot_small_floor' => 0.04,
+            'shoot_count_exp' => 0.65,
+            'mat' => 0.0,
+            'mat_opening_w' => 0,
+            'mat_opening_h' => 0,
+            'rotate' => 90,
+            'saturation' => 0.6,
+            'panel' => '',
+            'quiet_start' => 22,
+            'quiet_end' => 6,
+            'heal_hours' => 24,
+            'timeout' => 45,
+            'basic_user' => '',
+            'basic_pass' => '',
+        ];
+        if ($_SERVER['REQUEST_METHOD'] === 'POST') {
+            $input = json_decode(file_get_contents('php://input'), true);
+            if (!is_array($input)) {
+                http_response_code(400);
+                echo json_encode(['error' => 'invalid JSON']);
+                break;
+            }
+            $current = file_exists($cfg_path) ? json_decode(file_get_contents($cfg_path), true) : $defaults;
+            if (!is_array($current)) $current = $defaults;
+            $allowed = array_keys($defaults);
+            foreach ($input as $k => $v) {
+                if (in_array($k, $allowed, true)) $current[$k] = $v;
+            }
+            file_put_contents($cfg_path, json_encode($current, JSON_PRETTY_PRINT) . "\n");
+            echo json_encode($current);
+        } else {
+            $current = file_exists($cfg_path) ? json_decode(file_get_contents($cfg_path), true) : $defaults;
+            if (!is_array($current)) $current = $defaults;
+            echo json_encode(array_merge($defaults, $current));
+        }
+        break;
+    }
+
     default:
         http_response_code(404);
         echo json_encode(['error' => 'unknown action']);