Delete the legacy _convertUnitValue helper on the domain and the
duplicate convertUnitValue export on curveNormalizer; both were
identical to UnitPolicy.convert. Callers in flowController, the
curve normalizer, and buildQHCurve now go through this.unitPolicy.
The contract in .claude/refactor/CONTRACTS.md §6 named these as the
target migration; this finishes the rollout for rotatingMachine.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>