[feat] Add ownership filter to model browser (#7201)

## Summary
Adds a dropdown filter to the model browser that allows users to filter
assets by ownership (All, My models, Public models), based on the
`is_immutable` property.

## Changes
- **Filter UI**: Added ownership dropdown in
[AssetFilterBar.vue](src/platform/assets/components/AssetFilterBar.vue#L30-L38)
that only appears when user has uploaded models
- **Filter Logic**: Implemented `filterByOwnership` function in
[useAssetBrowser.ts](src/platform/assets/composables/useAssetBrowser.ts#L38-L45)
to filter by `is_immutable` property
- **i18n**: Added translation strings for ownership filter options
- **Tests**: Added comprehensive tests for ownership filtering in both
composable and component test files

## Review Focus
- The ownership filter visibility logic correctly checks for mutable
assets (`!is_immutable`)
- Default filter value is 'all' to show all models initially
- Filter integrates cleanly with existing file format and base model
filters

🤖 Generated with [Claude Code](https://claude.com/claude-code)

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-7201-feat-Add-ownership-filter-to-model-browser-2c16d73d365081f280f6d1e42e5400af)
by [Unito](https://www.unito.io)

---------

Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: GitHub Action <action@github.com>

src/platform/assets/composables/useAssetBrowser.ts

@@ -11,6 +11,8 @@ import {
   getAssetDescription
 } from '@/platform/assets/utils/assetMetadataUtils'
 
+export type OwnershipOption = 'all' | 'my-models' | 'public-models'
+
 function filterByCategory(category: string) {
   return (asset: AssetItem) => {
     return category === 'all' || asset.tags.includes(category)
@@ -35,6 +37,15 @@ function filterByBaseModels(models: string[]) {
   }
 }
 
+function filterByOwnership(ownership: OwnershipOption) {
+  return (asset: AssetItem) => {
+    if (ownership === 'all') return true
+    if (ownership === 'my-models') return asset.is_immutable === false
+    if (ownership === 'public-models') return asset.is_immutable === true
+    return true
+  }
+}
+
 type AssetBadge = {
   label: string
   type: 'type' | 'base' | 'size'
@@ -65,7 +76,8 @@ export function useAssetBrowser(
   const filters = ref<FilterState>({
     sortBy: 'recent',
     fileFormats: [],
-    baseModels: []
+    baseModels: [],
+    ownership: 'all'
   })
 
   // Transform API asset to display asset
@@ -176,6 +188,7 @@ export function useAssetBrowser(
     const filtered = searchFiltered.value
       .filter(filterByFileFormats(filters.value.fileFormats))
       .filter(filterByBaseModels(filters.value.baseModels))
+      .filter(filterByOwnership(filters.value.ownership))
 
     const sortedAssets = [...filtered]
     sortedAssets.sort((a, b) => {