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>

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

@@ -78,7 +78,7 @@
                     <input type="number" id="settings-send-latency" min="0" max="5000" value="0">
                 </div>
 
-                <div class="form-group">
+                <div class="form-group" id="settings-health-interval-group">
                     <div class="label-row">
                         <label for="settings-health-interval" data-i18n="settings.health_interval">Health Check Interval (s):</label>
                         <button type="button" class="hint-toggle" onclick="toggleHint(this)" title="?">?</button>
@@ -87,7 +87,7 @@
                     <input type="number" id="settings-health-interval" min="5" max="600" value="30">
                 </div>
 
-                <div class="form-group settings-toggle-group">
+                <div class="form-group settings-toggle-group" id="settings-auto-shutdown-group">
                     <div class="label-row">
                         <label data-i18n="settings.auto_shutdown">Auto Restore:</label>
                         <button type="button" class="hint-toggle" onclick="toggleHint(this)" title="?">?</button>
@@ -99,6 +99,18 @@
                     </label>
                 </div>
 
+                <div class="form-group" id="settings-ws-url-group" style="display: none;">
+                    <div class="label-row">
+                        <label for="settings-ws-url" data-i18n="device.ws_url">Connection URL:</label>
+                        <button type="button" class="hint-toggle" onclick="toggleHint(this)" title="?">?</button>
+                    </div>
+                    <small class="input-hint" style="display:none" data-i18n="device.ws_url.hint">WebSocket URL for clients to connect and receive LED data</small>
+                    <div class="ws-url-row">
+                        <input type="text" id="settings-ws-url" readonly>
+                        <button type="button" class="btn btn-sm btn-secondary" onclick="copyWsUrl()" title="Copy">&#x1F4CB;</button>
+                    </div>
+                </div>
+
                 <div id="settings-error" class="error-message" style="display: none;"></div>
             </form>
         </div>