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/integrations/schedule-schema.md

@@ -0,0 +1,93 @@
+# `.kaizen/schedule.yml` Schema
+
+The schedule manifest declares which kaizen agents run on what cadence in an
+opted-in repo. It is the repo-local half of the scheduled-agent-execution
+contract (ADR-005). activity-core reads it (via the roster resolver) to fire
+recurring tasks; `kaizen-agentic schedule prepare` reads it indirectly by
+preparing per-agent orientation.
+
+Canonical example: [`docs/examples/.kaizen/schedule.yml`](../examples/.kaizen/schedule.yml).
+
+## Location
+
+```
+<project-root>/.kaizen/schedule.yml
+```
+
+Lives alongside `.kaizen/agents/` (memory) and `.kaizen/metrics/`. Like those,
+its presence is the **opt-in signal** for fleet scheduling.
+
+## Fields
+
+| Key | Required | Type | Default | Notes |
+|-----|----------|------|---------|-------|
+| `version` | yes | string | — | Must be `"1"` |
+| `timezone` | no | string | from ActivityDefinition | IANA tz, e.g. `Europe/Berlin` |
+| `agents` | yes | mapping | — | `agent-name → settings` |
+| `agents.<name>.cadence` | yes | enum | — | `daily` \| `weekly` \| `monthly` |
+| `agents.<name>.cron` | no | string | cadence default | 5-field cron expression |
+| `agents.<name>.enabled` | no | bool | `true` | Set `false` to declare but pause |
+
+## Example
+
+```yaml
+version: "1"
+timezone: Europe/Berlin
+agents:
+  coach:
+    cadence: weekly
+    cron: "0 9 * * 1"
+    enabled: true
+  optimization:
+    cadence: weekly
+    cron: "0 10 * * 1"
+    enabled: true
+  tdd-workflow:
+    cadence: monthly
+    enabled: false
+```
+
+## Validation
+
+```bash
+kaizen-agentic schedule validate
+```
+
+Errors are emitted with actionable messages and a non-zero exit code:
+
+- Missing or non-`"1"` `version`.
+- `agents` not a mapping, or no agents declared.
+- An agent name that is **not** installed or packaged (typo guard).
+- A `cadence` outside `daily` / `weekly` / `monthly`.
+- Duplicate agent entries.
+
+Only agents available to the project (installed under `agents/` or packaged in
+the distribution) may appear in a schedule.
+
+## Scaffolding
+
+```bash
+kaizen-agentic schedule init                 # defaults: coach + optimization weekly
+kaizen-agentic schedule init --timezone UTC  # override timezone
+kaizen-agentic schedule init --force         # overwrite existing
+```
+
+The default scaffold enables `coach` and `optimization` weekly and declares
+`tdd-workflow` monthly but **disabled** (operator opts in deliberately).
+
+## Listing
+
+```bash
+kaizen-agentic schedule list        # enabled entries only
+kaizen-agentic schedule list --all  # include disabled
+```
+
+## Relationship to activity-core
+
+The `cron` field is an **optional per-repo override**. When omitted, the cadence
+maps to the default cron declared in the matching ActivityDefinition (e.g.
+`weekly-coach-orientation` fires Mon 09:00). This keeps fleet-wide timing in one
+place while letting individual repos shift their slot.
+
+See [ADR-005](../adr/ADR-005-scheduled-agent-execution.md) and
+[INTEGRATION_PATTERNS.md Pattern 2](../INTEGRATION_PATTERNS.md).