v1.24.0 — runner hardening + review-gate honesty (kindly adoption)

Adopted from the MIT-licensed "kindly" skill (ideas runner-hardening-kindly +
meta-protocol-change-review-gate-honesty):

• Agent supervision: first-output watchdog (120s, one retry), stall guard
  (30m, output-growth based), persisted agent.heartbeat events (60s; excluded
  from transcripts/triggers); counting writers — zero healthy-path I/O; typed
  agent.no_first_output/agent.stalled events appended BEFORE the kill.
  Config: first_event_timeout_ms, stall_timeout_ms, heartbeat_ms.
• Failure classification: agent.failed now carries failure_class +
  recovery_hint (rate-limit/auth/billing/overloaded/…); surfaced in the TUI
  narrator and agent headers.
• Artifact beats exit code: a validated artifact with an ordinary nonzero
  exit finishes with agent_exit instead of failing (removes the agy
  wrote-then-exit-1 flake); ACP validation now respects the run phase; fix-ups
  validate IMPLEMENTATION.md instead of trusting exit 0; Result.Success().
• Review snapshots: Phase 6 reviewers read a disposable shared-clone
  checkout on local tmp (dirty trees become temp-index snapshot commits);
  artifacts move back via copy+fsync+rename; loud fallback events.
• parley consult + parley consults list: advisory cross-agent questions
  with durable artifacts under parley-deck/consults/ (never quorum evidence).
• Hardening: claude participants shed nested host markers; read-only git probes
  set GIT_OPTIONAL_LOCKS=0; fsutil.AppendLine; docs/agent-cli-mechanics.md.
• Protocol: Phase 6 "Review briefs and dispositions" (no-suppression),
  Phase 8 opt-in strict_gate + "Stopping judgment", §8 "Consults" standing;
  mirrored to the embedded default protocol.