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>

src/components/common/StatusBadge.vue

@@ -0,0 +1,30 @@
+<script setup lang="ts">
+type Severity = 'default' | 'secondary' | 'warn' | 'danger' | 'contrast'
+
+const { label, severity = 'default' } = defineProps<{
+  label: string
+  severity?: Severity
+}>()
+
+function badgeClasses(sev: Severity): string {
+  const baseClasses =
+    'inline-flex h-3.5 items-center justify-center rounded-full px-1 text-xxxs font-semibold uppercase'
+
+  switch (sev) {
+    case 'danger':
+      return `${baseClasses} bg-destructive-background text-white`
+    case 'contrast':
+      return `${baseClasses} bg-base-foreground text-base-background`
+    case 'warn':
+      return `${baseClasses} bg-warning-background text-base-background`
+    case 'secondary':
+      return `${baseClasses} bg-secondary-background text-base-foreground`
+    default:
+      return `${baseClasses} bg-primary-background text-base-foreground`
+  }
+}
+</script>
+
+<template>
+  <span :class="badgeClasses(severity)">{{ label }}</span>
+</template>