fix: path_to_module to handle hidden files (e.g. .clang-tidy) correctly (#987)

It works fine with normal install `pip install .` but not for editable
install `pip install -e .`

I got the error below without this fix because it can't handle hidden
file's extension corretly:
```
    File "/opt/miniconda3/envs/pyapl/lib/python3.12/site-packages/scikit_build_core/build/_pathutil.py", line 31, in path_to_module
      path = path.with_name(path.name.split(".", 1)[0])
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    File "/opt/miniconda3/envs/pyapl/lib/python3.12/pathlib.py", line 634, in with_name
      raise ValueError("Invalid name %r" % (name))
  ValueError: Invalid name ''
```
For example, if it's `.clang-tidy`, the original splitting
`path.name.split(".", 1)[0]` results empty string.

---------

Signed-off-by: Henry Schreiner <[email protected]>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Henry Schreiner <[email protected]>

Author: 3 people

src/scikit_build_core/build/_editable.py

@@ -70,6 +70,7 @@ def libdir_to_installed(libdir: Path) -> dict[str, str]:
     Convert a mapping of files to modules to a mapping of modules to installed files.
     """
     return {
-        path_to_module(v.relative_to(libdir)): str(v.relative_to(libdir))
+        path_to_module(pth): str(pth)
         for v in scantree(libdir)
+        if is_valid_module(pth := v.relative_to(libdir))
     }

src/scikit_build_core/build/_pathutil.py

@@ -28,7 +28,9 @@ def scantree(path: Path) -> Generator[Path, None, None]:
 
 
 def path_to_module(path: Path) -> str:
-    path = path.with_name(path.name.split(".", 1)[0])
+    name, _, _ = path.name.partition(".")
+    assert name, f"Empty name should be filtered by is_valid_module first, got {path}"
+    path = path.with_name(name)
     if path.name == "__init__":
         path = path.parent
     return ".".join(path.parts)

tests/packages/navigate_editable/CMakeLists.txt

@@ -12,10 +12,13 @@ python_add_library(c_module MODULE src/shared_pkg/c_module.c WITH_SOABI)
 set(CMakeVar "Some_value_C")
 configure_file(src/shared_pkg/data/generated.txt.in
                shared_pkg/data/c_generated.txt)
+configure_file(src/shared_pkg/data/generated.txt.in shared_pkg/data/.hidden)
 
 install(
   TARGETS c_module
   DESTINATION shared_pkg/
   COMPONENT PythonModule)
 install(FILES ${PROJECT_BINARY_DIR}/shared_pkg/data/c_generated.txt
         DESTINATION shared_pkg/data/)
+install(FILES ${PROJECT_BINARY_DIR}/shared_pkg/data/.hidden
+        DESTINATION shared_pkg/data/)