fix: use immediate watcher to handle already-terminal downloads

Vue watch() is lazy by default — if the WS completion event
arrives before the watcher is registered, the callback never
fires. Adding { immediate: true } settles the existing state
on watcher creation.

src/platform/assets/composables/useUploadModelWizard.ts

@@ -275,7 +275,8 @@ export function useUploadModelWizard(modelTypes: Ref<ModelTypeOption[]>) {
               stopAsyncWatch?.()
               stopAsyncWatch = undefined
             }
-          }
+          },
+          { immediate: true }
         )
       } else {
         uploadStatus.value = 'success'