refactor(annotation): 简化文本标注编辑器的段落管理功能

- 移除段落统计相关的数据结构和缓存逻辑
- 删除段落切换确认对话框和自动保存选项
- 简化段落加载和状态管理流程
- 将段落列表视图替换为简单的进度显示
- 更新API接口以支持单段内容获取
- 重构后端服务实现单段内容查询功能

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

@@ -103,12 +103,25 @@ class EditorTaskResponse(BaseModel):
     model_config = ConfigDict(populate_by_name=True)
 
 
-class EditorTaskSegmentsResponse(BaseModel):
-    """编辑器段落摘要响应"""
+class SegmentDetail(BaseModel):
+    """段落内容"""
+
+    idx: int = Field(..., description="段落索引")
+    text: str = Field(..., description="段落文本")
+    has_annotation: bool = Field(False, alias="hasAnnotation", description="该段落是否已有标注")
+    line_index: int = Field(0, alias="lineIndex", description="JSONL 行索引（从0开始）")
+    chunk_index: int = Field(0, alias="chunkIndex", description="行内分片索引（从0开始）")
+
+    model_config = ConfigDict(populate_by_name=True)
+
+
+class EditorTaskSegmentResponse(BaseModel):
+    """编辑器单段内容响应"""
 
     segmented: bool = Field(False, description="是否启用分段模式")
-    segments: List[SegmentInfo] = Field(default_factory=list, description="段落摘要列表")
+    segment: Optional[SegmentDetail] = Field(None, description="段落内容")
     total_segments: int = Field(0, alias="totalSegments", description="总段落数")
+    current_segment_index: int = Field(0, alias="currentSegmentIndex", description="当前段落索引")
 
     model_config = ConfigDict(populate_by_name=True)