Add pytest configuration for namespace packages

Configure pytest to properly handle implicit namespace packages by:
- Enabling consider_namespace_packages option
- Using importlib import mode
- Setting pythonpath to src directory

This fixes module naming in test reports, ensuring tests are reported
with their full namespace path (e.g., node.tests.Foo instead of tests.Foo).

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: rnixx

pyproject.toml

@@ -37,5 +37,11 @@ Homepage = "http://github.com/conestack/node.ext.fs"
 
 [tool.hatch.build.targets.wheel]
 packages = ["src/node"]
+
+[tool.pytest.ini_options]
+consider_namespace_packages = true
+addopts = ["--import-mode=importlib"]
+pythonpath = "src"
+
 [tool.zest-releaser]
 create-wheel = true