feat: Add Deduplication Agent with embedding and LLM methods

Implement a new Deduplication Agent that identifies and groups similar
transformation descriptions. Supports two deduplication methods:
- Embedding: Fast vector similarity comparison using cosine similarity
- LLM: Accurate pairwise semantic comparison (slower but more precise)

Backend changes:
- Add deduplication router with /deduplicate endpoint
- Add embedding_service for vector-based similarity
- Add llm_deduplication_service for LLM-based comparison
- Improve expert_transformation error handling and progress reporting

Frontend changes:
- Add DeduplicationPanel with interactive group visualization
- Add useDeduplication hook for state management
- Integrate deduplication tab in main App
- Add threshold slider and method selector in sidebar

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

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

backend/app/routers/expert_transformation.py

@@ -221,8 +221,27 @@ async def generate_expert_transformation_events(
                     desc_prompt, model=model, temperature=temperature
                 )
 
-                desc_data = extract_json_from_response(desc_response)
-                desc_text = desc_data.get("description", "")
+                # 嘗試解析 JSON，若失敗則使用原始回應作為描述
+                desc_text = ""
+                try:
+                    desc_data = extract_json_from_response(desc_response)
+                    # 支援多種可能的 key: description, content, text, desc
+                    desc_text = (
+                        desc_data.get("description") or
+                        desc_data.get("content") or
+                        desc_data.get("text") or
+                        desc_data.get("desc") or
+                        ""
+                    )
+                except ValueError:
+                    # JSON 解析失敗，嘗試清理原始回應作為描述
+                    cleaned = desc_response.strip()
+                    # 移除可能的 markdown 和多餘符號
+                    if cleaned.startswith('"') and cleaned.endswith('"'):
+                        cleaned = cleaned[1:-1]
+                    if len(cleaned) > 5 and len(cleaned) < 100:
+                        desc_text = cleaned
+                        logger.info(f"[DESC] 使用 fallback 描述 for '{kw.keyword}': {desc_text[:50]}")
 
                 if desc_text:
                     descriptions.append(ExpertTransformationDescription(
@@ -231,15 +250,22 @@ async def generate_expert_transformation_events(
                         expert_name=kw.expert_name,
                         description=desc_text
                     ))
+                else:
+                    logger.warning(f"[DESC] Empty description for keyword='{kw.keyword}', parsed_data={desc_data}")
 
-                # Send progress update
-                yield f"event: description_progress\ndata: {json.dumps({'current': idx + 1, 'total': len(all_expert_keywords), 'keyword': kw.keyword}, ensure_ascii=False)}\n\n"
+                # Send progress update with success/fail status
+                yield f"event: description_progress\ndata: {json.dumps({'current': idx + 1, 'total': len(all_expert_keywords), 'keyword': kw.keyword, 'success': bool(desc_text)}, ensure_ascii=False)}\n\n"
 
             except Exception as e:
-                logger.warning(f"Failed to generate description for '{kw.keyword}': {e}")
+                logger.warning(f"[DESC] Failed to generate description for '{kw.keyword}': {e}")
+                yield f"event: description_progress\ndata: {json.dumps({'current': idx + 1, 'total': len(all_expert_keywords), 'keyword': kw.keyword, 'success': False, 'error': str(e)}, ensure_ascii=False)}\n\n"
                 # Continue with next keyword
 
-        yield f"event: description_complete\ndata: {json.dumps({'count': len(descriptions)}, ensure_ascii=False)}\n\n"
+        # 統計成功率
+        success_rate = len(descriptions) / len(all_expert_keywords) * 100 if all_expert_keywords else 0
+        logger.info(f"[DESC] 描述生成完成: {len(descriptions)}/{len(all_expert_keywords)} 成功 ({success_rate:.1f}%)")
+
+        yield f"event: description_complete\ndata: {json.dumps({'count': len(descriptions), 'total': len(all_expert_keywords), 'success_rate': success_rate}, ensure_ascii=False)}\n\n"
 
         # ========== Build final result ==========
         result = ExpertTransformationCategoryResult(