feat(annotation): 添加文本分段标注功能

- 引入文本分割器实现长文本按200字符自动分段
- 增加分段状态管理和段落导航界面
- 支持按段落保存和加载标注数据
- 实现分段模式下的标注状态跟踪
- 扩展API接口支持段落索引参数
- 添加分段相关的数据模型定义

runtime/datamate-python/app/module/annotation/interface/editor.py

@@ -9,6 +9,8 @@ Label Studio Editor（前端嵌入式）接口
 
 from __future__ import annotations
 
+from typing import Optional
+
 from fastapi import APIRouter, Depends, Query, Path
 from sqlalchemy.ext.asyncio import AsyncSession
 
@@ -67,10 +69,11 @@ async def list_editor_tasks(
 async def get_editor_task(
     project_id: str = Path(..., description="标注项目ID（t_dm_labeling_projects.id）"),
     file_id: str = Path(..., description="文件ID（t_dm_dataset_files.id）"),
+    segment_index: Optional[int] = Query(None, alias="segmentIndex", description="段落索引（分段模式下使用）"),
     db: AsyncSession = Depends(get_db),
 ):
     service = AnnotationEditorService(db)
-    task = await service.get_task(project_id, file_id)
+    task = await service.get_task(project_id, file_id, segment_index=segment_index)
     return StandardResponse(code=200, message="success", data=task)