fix: disconnect live data sources regardless of connection state when disabled

When a live data source server went down, EventSource entered the
CONNECTING (reconnecting) state. Disabling the source only called
disconnect() when isConnected() was true (readyState === OPEN),
so reconnecting sources were never stopped.

Closes #102

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

Author: ThomasHalwax

src/renderer/store/SSELayerStore.js

@@ -119,7 +119,7 @@ SSELayerStore.prototype.updateOrCreateService = function (key, service) {
     // Handle enabled state change
     if (service.enabled && service.url && !source.isConnected()) {
       source.connect()
-    } else if (!service.enabled && source.isConnected()) {
+    } else if (!service.enabled) {
       source.disconnect()
       source.clear()
     }