fix(frontend): address Copilot review feedback on HuggingFaceComponent

- Fix model polling indefinite loop by detecting cancelled in-flight fetch
- Fix CSS class mismatch: hf-tasks-error → hf-error to match SCSS
- Remove unused imports in spec file

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: ELin2025

frontend/src/app/workspace/component/hugging-face/hugging-face.component.html

@@ -36,7 +36,7 @@
   <!-- Tasks fetch error (non-blocking: static list is still shown) -->
   <div
     *ngIf="tasksError && !tasksLoading"
-    class="hf-tasks-error">
+    class="hf-error">
     <span class="error-text">{{ tasksError }}</span>
     <button
       nz-button

frontend/src/app/workspace/component/hugging-face/hugging-face.component.spec.ts

@@ -17,12 +17,7 @@
  * under the License.
  */
 
-import {
-  HuggingFaceComponent,
-  HuggingFaceModelOption,
-  STATIC_TASK_OPTIONS,
-  invalidateHuggingFaceModelCache,
-} from "./hugging-face.component";
+import { STATIC_TASK_OPTIONS, invalidateHuggingFaceModelCache } from "./hugging-face.component";
 
 describe("HuggingFaceComponent (unit)", () => {
   beforeEach(() => {

frontend/src/app/workspace/component/hugging-face/hugging-face.component.ts

@@ -332,9 +332,10 @@ export class HuggingFaceComponent extends FieldType<FieldTypeConfig> implements
     // Another instance is already fetching this task — wait for it
     if (inFlightByTag.has(tag)) {
       this.loading = true;
-      this.modelPollInterval = setInterval(() => {
+      if (this.modelPollInterval !== null) clearInterval(this.modelPollInterval);
+      const poll = setInterval(() => {
         if (allModelsByTag.has(tag) || errorByTag.has(tag)) {
-          clearInterval(this.modelPollInterval!);
+          clearInterval(poll);
           this.modelPollInterval = null;
           this.loading = false;
           if (allModelsByTag.has(tag)) {
@@ -345,8 +346,15 @@ export class HuggingFaceComponent extends FieldType<FieldTypeConfig> implements
             this.errorMessage = errorByTag.get(tag)!;
             this.cdr.detectChanges();
           }
+        } else if (!inFlightByTag.has(tag)) {
+          // Fetch was canceled before populating caches; stop polling and fall back.
+          clearInterval(poll);
+          this.modelPollInterval = null;
+          this.loading = false;
+          this.cdr.detectChanges();
         }
       }, 200);
+      this.modelPollInterval = poll;
       return;
     }