Drive all 4 remaining tasks to completion through full lifecycle

- actionable-phase-guidance: lifecycle artifacts + .state->complete
- harden-enforcement-layers: pre-push hook, install-hooks.sh, register-guards.sh, prompt pre-edit checks, harness contract update, install/update/upgrade script integration
- plug-stale-task-hole: lifecycle artifacts + .state->complete
- port-pi-guard: pi dev guard plugin, package.json, register-guards integration

All tasks passed bug_find, adversarial_bug_find, doc_review, and referee phases with PASS verdict.

tasks/actionable-phase-guidance/IMPLEMENTATION.md

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+# Phase Guidance Implementation
+
+## Summary
+Added actionable next-step guidance to all dashboard phases across the full stack.
+
+## Changes
+
+### automaton/dashboard/core/task.py
+- Added `phase_guidance` property to `Task` dataclass providing per-phase actionable guidance text
+- Added `blocker` property for identifying what blocks task progression
+- Added `required_artifact_name` and `next_phase_name` helper properties
+
+### automaton/dashboard/ui/app.py
+- Exposed `phase_guidance`, `blocker`, `required_artifact_name`, `next_phase_name` in the `/api/tasks` JSON response
+
+### automaton/dashboard/html/dashboard.js
+- Added "What's Next" section in the detail modal rendering `phase_guidance`
+- Added "What's Blocking" section rendering `blocker`
+- Added status reason display on task cards
+
+### automaton/dashboard/html/styles.css
+- Added `.detail-guidance`, `.detail-blocker`, `.detail-status-reason` CSS classes