feat: add model download progress dialog (#7897)

## Summary

Add a progress dialog for model downloads that appears when downloads
are active.

## Changes

- Add `ModelImportProgressDialog` component for showing download
progress
- Add `ProgressToastItem` component for individual download job display
- Add `StatusBadge` component for status indicators
- Extend `assetDownloadStore` with:
  - `finishedDownloads` computed for completed/failed jobs
  - `hasDownloads` computed for dialog visibility
  - `clearFinishedDownloads()` to dismiss finished downloads
- Dialog visibility driven by store state
- Closing dialog clears finished downloads
- Filter dropdown to show all/completed/failed downloads
- Expandable/collapsible UI with animated transitions
- Update AGENTS.md with import type convention and pluralization note

## Testing

- Start a model download and verify the dialog appears
- Verify expand/collapse animation works
- Verify filter dropdown works
- Verify closing the dialog clears finished downloads
- Verify dialog hides when no downloads remain

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-7897-feat-add-model-download-progress-dialog-2e26d73d36508116960eff6fbe7dc392)
by [Unito](https://www.unito.io)

---------

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

AGENTS.md

@@ -63,6 +63,9 @@ The project uses **Nx** for build orchestration and task management
 - Imports:
   - sorted/grouped by plugin
   - run `pnpm format` before committing
+  - use separate `import type` statements, not inline `type` in mixed imports
+    - ✅ `import type { Foo } from './foo'` + `import { bar } from './foo'`
+    - ❌ `import { bar, type Foo } from './foo'`
 - ESLint:
   - Vue + TS rules
   - no floating promises
@@ -137,7 +140,7 @@ The project uses **Nx** for build orchestration and task management
 8. Implement proper error handling
 9. Follow Vue 3 style guide and naming conventions
 10. Use Vite for fast development and building
-11. Use vue-i18n in composition API for any string literals. Place new translation entries in src/locales/en/main.json
+11. Use vue-i18n in composition API for any string literals. Place new translation entries in src/locales/en/main.json. Use the plurals system in i18n instead of hardcoding pluralization in templates.
 12. Avoid new usage of PrimeVue components
 13. Write tests for all changes, especially bug fixes to catch future regressions
 14. Write code that is expressive and self-documenting to the furthest degree possible. This reduces the need for code comments which can get out of sync with the code itself. Try to avoid comments unless absolutely necessary