[Copilot]

The macOS release check failed because testthat compared named bestmatch scalars with unnamed expected values. The named output is intentional; the assertions should compare values independently of names.

• Regression coverage: Add a focused test for coordmatchsing() selecting the nearest in-radius match.
• Test setup: Declare testthat and register the package test runner.
• Assertions: Strip names from extracted scalars before comparison:

  expect_equal(unname(matches$bestmatch["compareID"]), 2)
  expect_equal(unname(matches$bestmatch["sep"]), 0, tolerance = 1e-10)