feat(fish_api): SQLite 快照投递、日志与 watch 空闲告警

- 新增 SQLite：measure/health 快照、delivery_cursor 单消费者 pop；clear/start_fresh 可清空库
- biomass GET 仅返回约定 data 字段，X-Fish-Biomass-New 表示是否有新快照；poller 读响应头
- loguru 桥接 uvicorn，子进程 stdout 流式输出；format_json_pretty 与算法摘要日志
- measure/action watch 无新任务时限流 WARNING；watch_idle 共用逻辑
- 依赖 loguru；新增 db、logging_config、subprocess_run、watch_idle、启动脚本

FishMeasure: 更新 fish_video_weight_evaluation 与 predict_weigth_from_svo2；移除未用 refbox/segmentation 脚本
Made-with: Cursor

FishMeasure/segmentation/__init__.py

@@ -1,6 +0,0 @@
-"""
-Segmentation training/inference utilities.
-
-Currently focused on YOLOv8-seg (Ultralytics) and Labelme polygon annotations.
-"""
-