feat: scheduled agent execution via activity-core (WP-0006, v1.3.0)

Enable kaizen agents to run on a regular cadence against a preselected repo
roster, orchestrated by activity-core and prepared by kaizen-agentic — without
this repo owning cron, Temporal workers, or an LLM runtime.

CLI + module:
- src/kaizen_agentic/schedule.py — .kaizen/schedule.yml parse/validate/scaffold
- `kaizen-agentic schedule` group: init, validate, list, prepare <agent>
  (prepare bundles agent prompt + memory + metrics + repo pointers, offline)
- tests/test_schedule_cli.py — 15 tests

Contract & design:
- ADR-005 scheduled agent execution; schema doc + example manifest
- discover_kaizen_scheduled_repos resolver spec, state-hub roster fields,
  kaizen.schedule.prepared event payload, activity-core handoff checklist
- INTEGRATION_PATTERNS Pattern 2 extended with roster model

ActivityDefinition drafts (enabled: false):
- weekly-coach-orientation, weekly-optimization-review

Docs: agency-framework, CLI cheat sheet, PACKAGE_RELEASE runner prereqs,
EcosystemIntegration, CHANGELOG, TODO. Workplan closed (status: done).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docs/examples/.kaizen/schedule.yml

@@ -0,0 +1,17 @@
+# Kaizen scheduled agent execution manifest (ADR-005)
+# Declares which agents run on what cadence in this repo.
+# Validate with: kaizen-agentic schedule validate
+version: "1"
+timezone: Europe/Berlin
+agents:
+  coach:
+    cadence: weekly
+    cron: "0 9 * * 1" # Monday 09:00 — cross-agent orientation brief
+    enabled: true
+  optimization:
+    cadence: weekly
+    cron: "0 10 * * 1" # Monday 10:00 — agent performance review
+    enabled: true
+  tdd-workflow:
+    cadence: monthly
+    enabled: false # declared but paused; operator opts in deliberately