Add --showlocals to all pytest configurations - #1286

Add --showlocals option to pytest configurations across all projects to ensure consistent behavior when displaying local variables in test failures.

pytest does not merge addopts across configuration files - it uses the first configuration found. When running pytest from a subdirectory, the local pytest.ini or pyproject.toml takes precedence over the root config. To ensure --showlocals applies regardless of where pytest is invoked, we add it to each project's configuration:

• Root pytest.ini: applies when running from repository root
• cuda_core/pytest.ini: applies when running from cuda_core directory
• cuda_bindings/pyproject.toml: appended to existing addopts
• cuda_pathfinder/pyproject.toml: added new pytest.ini_options section

This approach ensures uniform pytest behavior across all projects while maintaining the ability to run tests from any directory.

Example behavior with --showlocals:

    def test_a_minus_b():
        a = float('inf')
        b = 1
        c = a - b
>       assert math.isfinite(c)
E       assert False
E        +  where False = <built-in function isfinite>(inf)
E        +    where <built-in function isfinite> = math.isfinite

a          = inf
b          = 1
c          = inf

tests/test_demo.py:5: AssertionError