v0.6.42 — Determinism guard — `reframe lint` now enforces scene purity

Added

Determinism guard — reframe lint now enforces scene purity

• Scenes must be pure functions of time (no Math.random()/Date), but nothing enforced
  it: a non-pure scene compiled to a different IR each time, silently breaking
  reproducibility (the golden tests only cover IR→render, not source→IR). reframe lint now
  closes that gap for .ts sources: it bundles the scene once, evaluates it twice, and
  emits a non-deterministic-render finding pinned to the first IR address that differs
  (e.g. nodes[0].props.x changed 0.42 → 0.97), with a hint at the culprit construct. Part
  of the same --strict gate as the addressability checks.
• New in-process API checkDeterminism(path) (exported via reframe-video/compile) →
  { deterministic, findings }, so an embedder can verify a freshly generated scene before
  trusting it. Additive: pure scenes report clean, and the check only runs on source inputs
  (.json is the IR itself). Implementation note: the two evals use distinct cache-busting
  comments to defeat Node's data:-URL ESM module cache (without which the second eval would
  return the cached module and miss module-level nondeterminism).