Pass explicit match path from match_features CLI

[yimingc]

Summary

This fixes the hloc.match_features CLI path mode for callers that provide explicit feature and match HDF5 paths.

match_features.main() already supports this mode through its matches argument: when features is a real file path, matches must also be provided as a path. The CLI also defines --matches, but the module entrypoint did not pass args.matches into main(), so explicit-path CLI calls failed before matching started.

This PR:

• adds a unit test that reproduces the explicit --features /path/features.h5 --matches /path/matches.h5 CLI path;
• passes args.matches from the CLI entrypoint into main();
• converts an existing string feature path to Path before passing it to match_from_paths().

Validation

Run locally with an environment that has hloc's runtime dependencies installed:

python -m unittest tests.test_match_features_cli
python -m py_compile hloc/match_features.py tests/test_match_features_cli.py

Result:

Ran 1 test in 0.786s
OK

I also checked that the existing name-based mode still returns the historical generated match filename pattern when pairs are empty and no model execution is needed.

[yimingc]

Updated the draft after local review:

• changed the final CLI entrypoint call to pass export_dir= and matches= as keyword arguments;
• kept the PR as two commits: one reproducing test, one fix;
• reran local validation with the hloc GPU venv used for this PR:
  • python -m unittest tests.test_match_features_cli
  • python -m py_compile hloc/match_features.py tests/test_match_features_cli.py
  • python -m black hloc/match_features.py tests/test_match_features_cli.py --check --diff
  • python -m flake8 hloc tests
  • git diff --check upstream/master...HEAD
  • Python scan for bidi control characters in changed files

All passed.