core/rules.py format-tolerant readers + stable registry (R001-R004 plan-scoped,
R100-R102 universal per LCD L33822). payer_rules.json wrapped in the same
commit as both engine readers (coupling hazard closed). Every DocItem now
cites the rule that decided it; NOT_EVALUATED cites nothing. Independent
audit: SHIP (registry-drift test added per its L2 finding). 138 tests green.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>