refactor: simplify asset download state and fix deletion UI (#7974)

## Summary

Refactors asset download state management and fixes asset deletion UI
issues.

## Changes

### assetDownloadStore simplification
- Replace `pendingModelTypes` Map with `modelType` stored directly on
`AssetDownload`
- Replace `completedDownloads` array with single `lastCompletedDownload`
ref
- `trackDownload()` now creates a placeholder entry immediately
- Use VueUse `whenever` instead of `watch` for cleaner null handling

### Asset refresh on download completion
- Refresh all relevant caches when a download completes:
  - Node type caches (e.g., "CheckpointLoaderSimple")
  - Tag caches (e.g., "tag:checkpoints")
  - "All Models" cache ("tag:models")

### Asset deletion fix
- Remove local `deletedLocal` state that caused blank grid cells
- Emit `deleted` event from AssetCard → AssetGrid → AssetBrowserModal
- Trigger store refresh on deletion to properly remove the asset from
the grid

## Testing

- Added test for out-of-order websocket message handling
- All existing tests pass

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-7974-refactor-simplify-asset-download-state-and-fix-deletion-UI-2e76d73d365081c69bcde9150a0d460c)
by [Unito](https://www.unito.io)

---------

Co-authored-by: Amp <amp@ampcode.com>

src/platform/assets/components/AssetBrowserModal.vue

@@ -57,6 +57,7 @@
         :assets="filteredAssets"
         :loading="isLoading"
         @asset-select="handleAssetSelectAndEmit"
+        @asset-deleted="refreshAssets"
       />
     </template>
   </BaseModalLayout>

src/platform/assets/components/AssetCard.vue

@@ -1,6 +1,5 @@
 <template>
   <div
-    v-if="!deletedLocal"
     data-component-id="AssetCard"
     :data-asset-id="asset.id"
     :aria-labelledby="titleId"
@@ -139,8 +138,9 @@ const { asset, interactive } = defineProps<{
   interactive?: boolean
 }>()
 
-defineEmits<{
+const emit = defineEmits<{
   select: [asset: AssetDisplayItem]
+  deleted: [asset: AssetDisplayItem]
 }>()
 
 const { t } = useI18n()
@@ -158,7 +158,6 @@ const descId = useId()
 
 const isEditing = ref(false)
 const newNameRef = ref<string>()
-const deletedLocal = ref(false)
 
 const displayName = computed(() => newNameRef.value ?? asset.name)
 
@@ -211,7 +210,7 @@ function confirmDeletion() {
           })
           // Give a second for the completion message
           await new Promise((resolve) => setTimeout(resolve, 1_000))
-          deletedLocal.value = true
+          emit('deleted', asset)
         } catch (err: unknown) {
           console.error(err)
           promptText.value = t('assetBrowser.deletion.failed', {

src/platform/assets/components/AssetGrid.vue

@@ -35,6 +35,7 @@
           :asset="item"
           :interactive="true"
           @select="$emit('assetSelect', $event)"
+          @deleted="$emit('assetDeleted', $event)"
         />
       </template>
     </VirtualGrid>
@@ -56,6 +57,7 @@ const { assets } = defineProps<{
 
 defineEmits<{
   assetSelect: [asset: AssetDisplayItem]
+  assetDeleted: [asset: AssetDisplayItem]
 }>()
 
 const assetsWithKey = computed(() =>

src/platform/assets/composables/useUploadModelWizard.ts

@@ -245,7 +245,8 @@ export function useUploadModelWizard(modelTypes: Ref<ModelTypeOption[]>) {
           if (selectedModelType.value) {
             assetDownloadStore.trackDownload(
               result.task.task_id,
-              selectedModelType.value
+              selectedModelType.value,
+              filename
             )
           }
           uploadStatus.value = 'processing'