Adds platform infrastructure used by the upcoming refactor of
nodeClass / specificClass across all 12 nodes:
- src/domain/UnitPolicy.js — extracted from rotatingMachine/MGC
- src/domain/ChildRouter.js — declarative event routing on top of childRegistrationUtils
- src/domain/LatestWinsGate.js — extracted from MGC dispatch gate
- src/domain/HealthStatus.js — standardised {level, flags, message, source}
- src/nodered/statusBadge.js — compose / error / idle / byState / text helpers
- src/stats/index.js — mean / stdDev / median / mad / lerp
All additive — no existing exports change shape.
56 unit tests pass under node:test.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
