[feat] Add active jobs display to grid view (#8209)

## Summary
Show active jobs in grid view matching the list view behavior, with
refactored component structure.

## Changes
- **ActiveJobCard**: New component for grid view job display with
progress bar
- **AssetsSidebarGridView**: Extracted grid view logic from
AssetsSidebarTab (matching ListView pattern)
- **Progress styling**: Use `useProgressBarBackground` composable for
consistent progress bar styling
- **Assets header**: Add "Generated/Imported assets" header in grid view

src/components/sidebar/tabs/AssetsSidebarListView.vue

@@ -2,7 +2,7 @@
   <div class="flex h-full flex-col">
     <div
       v-if="activeJobItems.length"
-      class="flex max-h-[50%] flex-col gap-2 overflow-y-auto px-2"
+      class="flex max-h-[50%] scrollbar-custom flex-col gap-2 overflow-y-auto px-2"
     >
       <AssetsListItem
         v-for="job in activeJobItems"
@@ -114,7 +114,7 @@ import AssetsListItem from '@/platform/assets/components/AssetsListItem.vue'
 import { getOutputAssetMetadata } from '@/platform/assets/schemas/assetMetadataSchema'
 import type { AssetItem } from '@/platform/assets/schemas/assetSchema'
 import { iconForMediaType } from '@/platform/assets/utils/mediaIconUtil'
-import type { JobState } from '@/types/queue'
+import { isActiveJobState } from '@/utils/queueUtil'
 import {
   formatDuration,
   formatSize,
@@ -172,12 +172,6 @@ const listGridStyle = {
   gap: '0.5rem'
 }
 
-function isActiveJobState(state: JobState): boolean {
-  return (
-    state === 'pending' || state === 'initialization' || state === 'running'
-  )
-}
-
 function getAssetPrimaryText(asset: AssetItem): string {
   return truncateFilename(asset.name)
 }