feat(api): 叙事 prompt、职业上下文、读路径章节、WS 解耦与错误脱敏

- 回忆录：事实边界补充允许清单；传记文体示例与 JSON 叙事要求对齐
- default 职业提示 occupation_context；cadre/military 退休语境
- GET 章节读路径零写入，prepare_chapter_read_view + markdown_for_response
- 文本归一抽到 core/text_normalize；移除弃用 reply 策略与 recompose_chapters_for_story
- ConversationService：WS 连接/用户段落/结束对话；对外错误固定文案
- 测试：HTTP 脱敏契约、章节读视图、occupation 与 background_voice

api/app/features/payment/router.py

@@ -66,7 +66,7 @@ async def wechat_notify(
         )
     except Exception as e:
         logger.exception("微信支付回调处理失败: {}", e)
-        return {"code": "FAIL", "message": str(e)}
+        return {"code": "FAIL", "message": "处理失败"}
 
 
 @router.post("/notify/alipay", include_in_schema=False)