feat(ui): merge user tags into auto-tag badges and refresh on tag edit (#918)

- Layer 2 fallback: user tags overlapping with auto-tag categories
  (HIGH/LOW/I2V/T2V/TI2V/Lightning/Turbo) are merged into auto_tags,
  providing manual override when filename-based detection fails.
  Matching is case-insensitive so "high"/"High"/"HIGH" all work.
- Refresh on tag edit: save_metadata and add_tags handlers now return
  recalculated auto_tags in the response; the frontend passes them to
  VirtualScroller.updateSingleItem so badges update immediately without
  requiring a page reload.
- 8 new test cases for Layer 2 fallback and case-insensitive matching.

static/js/api/baseModelApi.js

@@ -422,8 +422,12 @@ export class BaseModelApiClient {
                 throw new Error('Failed to save metadata');
             }
 
-            state.virtualScroller.updateSingleItem(filePath, data);
-            return response.json();
+            const result = await response.json();
+            state.virtualScroller.updateSingleItem(filePath, {
+                ...data,
+                auto_tags: result.auto_tags,
+            });
+            return result;
         } finally {
             state.loadingManager.hide();
         }
@@ -448,7 +452,10 @@ export class BaseModelApiClient {
             const result = await response.json();
 
             if (result.success && result.tags) {
-                state.virtualScroller.updateSingleItem(filePath, { tags: result.tags });
+                state.virtualScroller.updateSingleItem(filePath, {
+                    tags: result.tags,
+                    auto_tags: result.auto_tags,
+                });
             }
 
             return result;