awf v0.5.2

A documentation-only patch release adding a clean-room Claude Code subscription
readiness path. There are no runtime or workflow-format changes.

Added

• Claude Code gated readiness example. A public workflow invokes the host
  Claude Code CLI as a black box from one AWF agent step, validates its typed
  output, and passes it through an independent deterministic gate. Generator
  and evaluator retries plus the gate attempt limit are each set to one, so AWF
  performs no orchestration-level reruns. The accompanying guide documents
  private claude setup-token handoff, the explicit native backend, the
  macOS-safe absolute state directory, gate-scoped output inspection, cleanup,
  and troubleshooting.