fix(native-messaging): suppress "Native host has exited" console error

Read runtime.lastError in the onDisconnect callback so Chrome does not
log "Unchecked runtime.lastError: Native host has exited" to the
extensions console. The disconnect reason is forwarded to debugLog so
it remains visible when Debug Mode is enabled.

extension/background/native-messaging.js

@@ -220,7 +220,12 @@ function connect() {
   });
 
   port.onDisconnect.addListener(() => {
-    debugLog('onDisconnect');
+    // Reading lastError suppresses the "Unchecked runtime.lastError: Native host has exited"
+    // console error that Chrome logs when the host process exits unexpectedly.
+    const disconnectReason = browser.runtime.lastError?.message || null;
+    if (disconnectReason) {
+      debugLog('onDisconnect reason:', disconnectReason);
+    }
     log('Native host disconnected');
     extensionState.hostConnected = false;
     activeConnections.clear();