fix: clarify toast - gateway restart required for platform toggle changes

app/src/main/java/com/m57/hermescontrol/ui/channels/ChannelsViewModel.kt

@@ -62,7 +62,7 @@ class ChannelsViewModel : ViewModel() {
                 }
             when (result) {
                 is NetworkResult.Success -> {
-                    _uiState.update { it.copy(isLoading = false, toastMessage = "$platformId configured successfully") }
+                    _uiState.update { it.copy(isLoading = false, toastMessage = "$platformId configured successfully — restart the gateway for changes to take effect") }
                     loadPlatforms()
                 }