feat: [FL-104][高程数据管理中文件明细要展示各个文件的坐标范围]

- 添加 ElevationDatasetFileMeta 数据库模型存储文件级别坐标范围
- 更新 API schema 和 service，返回每个文件的 bbox 信息
- 修改高程数据分析任务，遍历目录所有文件并提取坐标范围
- 前端文件明细表格新增坐标范围列
- 创建数据库迁移脚本

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Co-authored-by: multica-agent <github@multica.ai>

migrations/add_elevation_file_meta.sql

@@ -0,0 +1,25 @@
+-- Migration: Add elevation_dataset_file_meta table for storing file-level coordinate ranges
+-- Date: 2026-06-13
+-- Description: Create new table to store bbox and metadata for each elevation file in a dataset
+
+CREATE TABLE IF NOT EXISTS elevation_dataset_file_meta (
+    id VARCHAR(32) PRIMARY KEY,
+    dataset_id VARCHAR(32) NOT NULL,
+    file_path VARCHAR(2048) NOT NULL,
+    file_name VARCHAR(512) NOT NULL,
+    bbox_min_lon DOUBLE PRECISION,
+    bbox_max_lon DOUBLE PRECISION,
+    bbox_min_lat DOUBLE PRECISION,
+    bbox_max_lat DOUBLE PRECISION,
+    sample_count INTEGER DEFAULT 0,
+    create_date TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT NOW(),
+    update_date TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT NOW(),
+    FOREIGN KEY (dataset_id) REFERENCES elevation_dataset(id) ON DELETE CASCADE
+);
+
+CREATE INDEX idx_elevation_file_meta_dataset ON elevation_dataset_file_meta(dataset_id);
+CREATE INDEX idx_elevation_file_meta_path ON elevation_dataset_file_meta(dataset_id, file_path);
+
+-- Notes:
+-- After running this migration, run the elevation dataset analysis task for each dataset
+-- to populate the file metadata with coordinate ranges.