0.2.0 — Drift detection + Node 20 fix

Added

• Upstream drift detection (.github/workflows/upstream-drift.yml):
  weekly CI that regenerates the golden fixtures from live fpv-sim main
  and fails if engagement outcomes differ from the committed ones —
  distinguishing engine regressions (npm test) from upstream
  behavior changes (fixture comparison). Also warns when the pinned
  design-notes snapshot falls behind upstream.

Fixed

• npm test now works on Node 20, the stated minimum: the test glob is
  shell-expanded instead of relying on node --test pattern expansion,
  which only Node 21+ performs. Caught by the drift workflow's first CI
  run.

Docs

• README example transcript: added a postscript correcting the agent's
  closing guess that the 6-second launch stagger explained the residual
  BLUFOR edge — a 2,000-pair study on this engine
  (fpv-sim's MONTE_CARLO.md,
  experiment E2c) found the stagger moves outcome rates by less than half
  a point.