v0.1.0

Initial public release. Semantic diff for HL7 v2 pipe-delimited messages — see which field changed, by name. Minimal stdlib-only parser. CLI hl7diff with text and json output formats. Static browser tool included for client-side diffing. HL7 v2.6 field labels for MSH, EVN, PID, PV1, OBR, OBX, NK1, AL1, DG1, IN1. 13 unit tests passing, ruff clean, mypy --strict clean. PyPI: https://pypi.org/project/hl7-message-diff/0.1.0/ (upload pending account rate-limit clearance — wheel + sdist attached to this release as evidence).