v0.21.0 — one command, the whole chain green

A launch-review pass (multi-agent, adversarially verified) found the first-contact story promised more than one command delivered. The fix is in the product, not the copy: the demo path now is one command.

• init --example ends by running the gate itself. After scaffolding the filled request-triage reference, init --example chains check --strict on the fresh mission — the whole chain goes green in front of you, in one command, exactly as advertised. Deterministic, zero-network, skipped under --dry-run. The example's next-steps now point at the guard demo (cd code && npm install && npm run demo — req-005 carries a fabricated account reference the deterministic guard refuses, fail-closed) instead of asking you to run a check that already ran.
• README accuracy pass (the HN landing). The hand-over uniqueness claim is aligned with the project's own sourced comparison (Spec Kitty does carry the mission past tested code; runward's difference is a plain-code succession check and standardized OSCAL evidence, not bespoke YAML). "FDE" is expanded on first use (Forward Deployed Engineer), the Why section leads with what runward does, and the sourced comparison + dropyour case study are linked from the Documentation list.
• Example docs. The reference floor's README now counts all five demo requests, including the guard-refused fabrication.

Full changelog: CHANGELOG.md