v5.3.1

[5.3.1] - 2026-07-20

Windows validation lore keeps the single-version harness release portable:

• Activation's symbolic-link safety test now unlinks the link itself with the
  cross-platform filesystem primitive instead of asking Bun to recursively
  remove a Windows directory link.
• The persistence integration test that exercises four pinned-helper closure
  paths now has an explicit 30-second budget, matching the existing
  process-spawning integration gates without weakening production timeouts.