Orthogonal boolean column alongside category, computed in classifier.py's
new is_medical_center(). Always flags MED CTR-tagged titles and the
existing HS CLIN PROF/-HCOMP patterns regardless of campus; additionally
flags generic clinical-workforce titles (physicians, nurses, dentists,
pharmacists, therapists, techs, etc.) only at the five campuses that
operate a UC-owned academic medical center (UCSF, UCLA, UCD, UCI, UCSD),
since those titles are indistinguishable from Student Health Services
staff elsewhere. SHS-tagged titles are always excluded.
Threaded through as a --group-by dimension for --aggregate-output and
as a column on --top-earners-output rows, alongside the per-employee CSV.
