Add WebSocket device type, capability-driven settings, hide filter on collapse

- New WS device type: broadcaster singleton + LEDClient that sends binary
  frames to connected WebSocket clients during processing
- FastAPI WS endpoint at /api/v1/devices/{device_id}/ws with token auth
- Frontend: add/edit WS devices, connection URL with copy button in settings
- Add health_check and auto_restore capabilities to WLED and Serial providers;
  hide health interval and auto-restore toggle for devices without them
- Skip health check loop for virtual devices (Mock, MQTT, WS) — set always-online
- Copy buttons and labels for API CSS push endpoints (REST POST / WebSocket)
- Hide mock:// and ws:// URLs in target device dropdown
- Hide filter textbox when card section is collapsed (cs-collapsed CSS class)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/wled_controller/templates/modals/add-device.html

@@ -31,6 +31,7 @@
                         <option value="adalight">Adalight</option>
                         <option value="ambiled">AmbiLED</option>
                         <option value="mqtt">MQTT</option>
+                        <option value="ws">WebSocket</option>
                         <option value="mock">Mock</option>
                     </select>
                 </div>