refactor: 重构项目结构，将geo_tools重命名为app并更新相关引用

- 将主包名从geo_tools改为app
- 更新所有模块中的引用路径
- 迁移并更新测试用例
- 添加项目规则文档
- 保持原有功能不变，仅进行结构调整

tests/test_io.py

@@ -4,8 +4,8 @@ import pytest
 import geopandas as gpd
 from pathlib import Path
 
-from geo_tools.io.readers import read_vector, read_gpkg, list_gpkg_layers, read_csv_points
-from geo_tools.io.writers import write_vector, write_gpkg, write_csv
+from app.io.readers import read_vector, read_gpkg, list_gpkg_layers, read_csv_points
+from app.io.writers import write_vector, write_gpkg, write_csv
 
 
 class TestReadVector:
@@ -61,7 +61,7 @@ class TestWriteReadRoundtrip:
         assert "geometry" in df.columns          # 存在 WKT 几何列
         assert len(df) == len(sample_points_gdf)  # 行数一致
         # 再用 read_csv_points 以 WKT 模式读回
-        from geo_tools.io.readers import _read_csv_vector
+        from app.io.readers import _read_csv_vector
         from pathlib import Path
         gdf_back = _read_csv_vector(Path(out), wkt_col="geometry")
         assert len(gdf_back) == len(sample_points_gdf)