feat: 更新章节排序逻辑

- 在process_memoir_segments和generate_chapter_content方法中，根据阶段计算章节的排序索引
- 引入CHAPTER_ORDER常量以确保章节顺序的正确性

api/tasks/memoir_tasks.py

@@ -21,6 +21,7 @@ from agents.prompts.memory_prompts import (
     get_creative_title_prompt,
     get_narrative_prompt,
     get_state_extraction_prompt,
+    CHAPTER_ORDER,
 )
 
 logger = logging.getLogger(__name__)
@@ -262,12 +263,14 @@ def process_memoir_segments(self, user_id: str, segment_ids: List[str]):
                     chapter.is_new = True
                     chapter.source_segments = list({*(chapter.source_segments or []), *source_ids})
                 else:
+                    # 根据 stage 计算正确的排序索引
+                    calculated_order_index = CHAPTER_ORDER.index(stage) if stage in CHAPTER_ORDER else 999
                     chapter = Chapter(
                         id=str(uuid.uuid4()),
                         user_id=user_id,
                         title=title,
                         content=narrative,
-                        order_index=999,
+                        order_index=calculated_order_index,
                         status="completed",
                         category=stage,
                         images=[],
@@ -363,12 +366,14 @@ def generate_chapter_content(self, user_id: str, stage: str, new_content: str):
                 chapter.content = narrative
                 chapter.is_new = True
             else:
+                # 根据 stage 计算正确的排序索引
+                calculated_order_index = CHAPTER_ORDER.index(stage) if stage in CHAPTER_ORDER else 999
                 chapter = Chapter(
                     id=str(uuid.uuid4()),
                     user_id=user_id,
                     title=f"{stage} 回忆",
                     content=narrative,
-                    order_index=999,
+                    order_index=calculated_order_index,
                     status="completed",
                     category=stage,
                     images=[],