fix: invalidate loader node dropdown cache after model asset deletion

When deleting a model asset (checkpoint, lora, etc.), the loader node
dropdowns now update correctly by invalidating the category-keyed cache.

- After deletion, check asset tags for model categories (checkpoints, loras, etc.)
- Call invalidateCategory() for each affected category
- Add tests for deletion invalidation behavior

Fixes the bug where deleted models still appeared in loader node dropdowns.

Co-authored-by: Amp <amp@ampcode.com>
Amp-Thread-ID: https://ampcode.com/threads/T-019c08a2-6a9f-770f-994c-ad79d515f6a1

src/platform/assets/composables/useMediaAssetActions.test.ts

@@ -293,6 +293,8 @@ describe('useMediaAssetActions', () => {
 
       await actions.deleteAssets(modelAsset)
 
+      // Only 'checkpoints' has providers; 'models' tag should not trigger invalidation
+      expect(mockInvalidateModelsForCategory).toHaveBeenCalledTimes(1)
       expect(mockInvalidateModelsForCategory).toHaveBeenCalledWith(
         'checkpoints'
       )