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

app/__init__.py

@@ -0,0 +1,63 @@
+"""
+geo_tools
+~~~~~~~~~
+专业地理信息数据处理工具库。
+
+核心依赖：geopandas、shapely、fiona、pyproj。
+
+快速开始
+--------
+>>> from geo_tools.io import readers
+>>> from geo_tools.core import vector
+>>> gdf = readers.read_vector("data/sample/sample_points.geojson")
+>>> gdf_proj = vector.reproject(gdf, "EPSG:3857")
+>>> print(gdf_proj.crs)
+
+GDB 读写
+--------
+>>> from geo_tools.io import readers, writers
+>>> layers = readers.list_gdb_layers("path/to/data.gdb")
+>>> gdf = readers.read_gdb("path/to/data.gdb", layer="my_layer")
+>>> writers.write_gdb(gdf, "output/result.gdb", layer="result_layer")
+
+要素类投影
+----------
+>>> from geo_tools.core import projection
+>>> gdf_proj = projection.reproject_gdf(gdf, "EPSG:4490")
+>>> gdf_utm  = projection.reproject_gdf(gdf, auto_utm=True)
+"""
+
+from importlib.metadata import PackageNotFoundError, version
+
+# ── 版本 ──────────────────────────────────────────────────────────────────────
+try:
+    __version__ = version("geo-tools")
+except PackageNotFoundError:
+    __version__ = "0.1.0-dev"
+
+# ── 配置 & 日志 ───────────────────────────────────────────────────────────────
+from .io import readers, writers
+from .config.settings import settings
+from .utils.logger import get_logger, set_global_level
+from .utils.validators import (
+    SUPPORTED_VECTOR_EXTENSIONS,
+    is_supported_vector_format,
+    is_valid_crs,
+    validate_crs,
+    validate_geometry,
+    validate_vector_path,
+)
+
+__all__ = [
+    "__version__",
+    "settings",
+    # utils
+    "get_logger",
+    "set_global_level",
+    "is_valid_crs",
+    "validate_crs",
+    "validate_geometry",
+    "is_supported_vector_format",
+    "validate_vector_path",
+    "SUPPORTED_VECTOR_EXTENSIONS",
+]