Phase 5: Add Timeline View feature

- Add backend API endpoints for timeline data:
  - GET /api/v1/projects/{id}/timeline
  - GET /api/v1/projects/{id}/timeline/summary
  - GET /api/v1/entities/{id}/timeline

- Add database methods for timeline queries in db_manager.py

- Add frontend timeline view:
  - New sidebar button for timeline view
  - Timeline panel with date-grouped events
  - Visual distinction between mentions and relations
  - Entity filter dropdown
  - Statistics cards
  - Interactive event cards

- Update STATUS.md with Phase 5 progress
- Add view switching functions (switchView, switchKBTab)
- Add knowledge base loading functions

backend/main.py

@@ -1265,3 +1265,72 @@ async def search_entities(project_id: str, q: str):
     db = get_db_manager()
     entities = db.search_entities(project_id, q)
     return [{"id": e.id, "name": e.name, "type": e.type, "definition": e.definition} for e in entities]
+
+
+# ==================== Phase 5: 时间线视图 API ====================
+
+@app.get("/api/v1/projects/{project_id}/timeline")
+async def get_project_timeline(
+    project_id: str, 
+    entity_id: str = None,
+    start_date: str = None,
+    end_date: str = None
+):
+    """获取项目时间线 - 按时间顺序的实体提及和关系事件"""
+    if not DB_AVAILABLE:
+        raise HTTPException(status_code=500, detail="Database not available")
+    
+    db = get_db_manager()
+    project = db.get_project(project_id)
+    if not project:
+        raise HTTPException(status_code=404, detail="Project not found")
+    
+    timeline = db.get_project_timeline(project_id, entity_id, start_date, end_date)
+    
+    return {
+        "project_id": project_id,
+        "events": timeline,
+        "total_count": len(timeline)
+    }
+
+
+@app.get("/api/v1/projects/{project_id}/timeline/summary")
+async def get_timeline_summary(project_id: str):
+    """获取项目时间线摘要统计"""
+    if not DB_AVAILABLE:
+        raise HTTPException(status_code=500, detail="Database not available")
+    
+    db = get_db_manager()
+    project = db.get_project(project_id)
+    if not project:
+        raise HTTPException(status_code=404, detail="Project not found")
+    
+    summary = db.get_entity_timeline_summary(project_id)
+    
+    return {
+        "project_id": project_id,
+        "project_name": project.name,
+        **summary
+    }
+
+
+@app.get("/api/v1/entities/{entity_id}/timeline")
+async def get_entity_timeline(entity_id: str):
+    """获取单个实体的时间线"""
+    if not DB_AVAILABLE:
+        raise HTTPException(status_code=500, detail="Database not available")
+    
+    db = get_db_manager()
+    entity = db.get_entity(entity_id)
+    if not entity:
+        raise HTTPException(status_code=404, detail="Entity not found")
+    
+    timeline = db.get_project_timeline(entity.project_id, entity_id)
+    
+    return {
+        "entity_id": entity_id,
+        "entity_name": entity.name,
+        "entity_type": entity.type,
+        "events": timeline,
+        "total_count": len(timeline)
+    }