match_members() now short-circuits on whole-word full-name hits and
uses word-boundary regex everywhere else, so a nickname that is a
substring of another member's surname (e.g. "tov" inside "ottova")
no longer produces false positives. Adds tests/test_match_members.py.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
