feat: implement batch import recipe functionality (frontend + backend fixes)

Backend fixes:
- Add missing API route for /api/lm/recipes/batch-import/progress (GET)
- Add missing API route for /api/lm/recipes/batch-import/directory (POST)
- Add missing API route for /api/lm/recipes/browse-directory (POST)
- Register WebSocket endpoint for batch import progress
- Fix skip_no_metadata default value (True -> False) to allow no-LoRA imports
- Add items array to BatchImportProgress.to_dict() for detailed results

Frontend implementation:
- Create BatchImportManager.js with complete batch import workflow
- Add directory browser UI for selecting folders
- Add batch import modal with URL list and directory input modes
- Implement real-time progress tracking (WebSocket + HTTP polling)
- Add results summary with success/failed/skipped statistics
- Add expandable details view showing individual item status
- Auto-refresh recipe list after import completion

UI improvements:
- Add spinner animation for importing status
- Simplify results summary UI to match progress stats styling
- Fix current item text alignment
- Fix dark theme styling for directory browser button
- Fix batch import button styling consistency

Translations:
- Add batch import related i18n keys to all locale files
- Run sync_translation_keys.py to sync all translations

Fixes:
- Batch import now allows images without LoRAs (matches single import behavior)
- Progress endpoint now returns complete items array with status details
- Results view correctly displays skipped items with error messages

static/js/managers/ModalManager.js

@@ -134,6 +134,19 @@ export class ModalManager {
             });
         }
 
+        // Add batchImportModal registration
+        const batchImportModal = document.getElementById('batchImportModal');
+        if (batchImportModal) {
+            this.registerModal('batchImportModal', {
+                element: batchImportModal,
+                onClose: () => {
+                    this.getModal('batchImportModal').element.style.display = 'none';
+                    document.body.classList.remove('modal-open');
+                },
+                closeOnOutsideClick: true
+            });
+        }
+
         // Add recipeModal registration
         const recipeModal = document.getElementById('recipeModal');
         if (recipeModal) {