feat: add import error tracking and translation tabs

Import Error Tracking:
- Add MarketplaceImportError model to store detailed error information
- Store row number, identifier, error type, message, and row data for each error
- Add API endpoint GET /admin/marketplace-import-jobs/{job_id}/errors
- Add UI to view and browse import errors in job details modal
- Support pagination and error type filtering

Translation Tabs:
- Replace flat translation list with tabbed interface on product detail page
- Add language tabs with full language names
- Add copy-to-clipboard functionality for translation content
- Improved UX with better visual separation of translations

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

static/admin/js/marketplace-product-detail.js

@@ -176,6 +176,53 @@ function adminMarketplaceProductDetail() {
             } catch (e) {
                 return dateString;
             }
+        },
+
+        /**
+         * Get full language name from ISO code
+         */
+        getLanguageName(code) {
+            const languages = {
+                'en': 'English',
+                'de': 'German',
+                'fr': 'French',
+                'lb': 'Luxembourgish',
+                'es': 'Spanish',
+                'it': 'Italian',
+                'nl': 'Dutch',
+                'pt': 'Portuguese',
+                'pl': 'Polish',
+                'cs': 'Czech',
+                'da': 'Danish',
+                'sv': 'Swedish',
+                'fi': 'Finnish',
+                'no': 'Norwegian',
+                'hu': 'Hungarian',
+                'ro': 'Romanian',
+                'bg': 'Bulgarian',
+                'el': 'Greek',
+                'sk': 'Slovak',
+                'sl': 'Slovenian',
+                'hr': 'Croatian',
+                'lt': 'Lithuanian',
+                'lv': 'Latvian',
+                'et': 'Estonian'
+            };
+            return languages[code?.toLowerCase()] || '';
+        },
+
+        /**
+         * Copy text to clipboard
+         */
+        async copyToClipboard(text) {
+            if (!text) return;
+            try {
+                await navigator.clipboard.writeText(text);
+                Utils.showToast('Copied to clipboard', 'success');
+            } catch (err) {
+                adminMarketplaceProductDetailLog.error('Failed to copy to clipboard:', err);
+                Utils.showToast('Failed to copy to clipboard', 'error');
+            }
         }
     };
 }