[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/locales/en/main.json

@@ -709,6 +709,7 @@
     "noGeneratedFiles": "No generated files found",
     "generatedAssetsHeader": "Generated assets",
     "importedAssetsHeader": "Imported assets",
+    "activeJobStatus": "Active job: {status}",
     "noFilesFoundMessage": "Upload files or generate content to see them here",
     "browseTemplates": "Browse example templates",
     "openWorkflow": "Open workflow in local file system",