feat(cli): add campaign management cmds, specs, and examples

[mnkiefer]

First-class Campaigns for Enterprises

Adds first‑class campaigns to gh-aw so enterprises can describe initiatives in specs (owners, risk, governance, metrics) while reusing existing workflows.

Campaign specs (*.campaign.md)

• Treat each campaign as a first‑class object defined in Markdown with YAML frontmatter, with:
  • id, name, description
  • workflows (one or many workflow IDs)
  • owners, executive_sponsors, risk_level, state, tags
  • tracker_label, memory_paths, metrics_glob
  • allowed_safe_outputs, approval_policy
• Support:
  • Single‑workflow campaigns like incident-response and security-compliance
  • A multi‑workflow campaign org-modernization that coordinates:
    • org-wide-rollout (rollout coordinator)
    • human-ai-collaboration (human‑in‑loop approvals)
    • intelligence (reporting / trend analysis)

gh aw campaign CLI

• gh aw campaign / gh aw campaign --json
  List all campaigns defined in campaigns/*.campaign.md.
• gh aw campaign status / --json
  Show compiled workflow state and basic issue/PR metrics grouped by tracker_label.
• gh aw campaign validate
  Validate specs (supports JSON output and non‑strict reporting).
• gh aw campaign new <id>
  Scaffold a new campaign spec file under campaigns/<id>.campaign.md.

Docs & examples

• Updates docs/src/content/docs/guides/campaigns.md to:
  • Explain how campaigns add ownership, governance, and reporting on top of existing workflows and repo‑memory.
  • Show both single‑workflow and multi‑workflow campaign spec examples.

[pelikhan]

Best to avoid the "example-" pattern, instead we want to have campaign that are actually useful to gh-aw. We have lots of issues, it's triage them through campaigns. Examples rot, useful tools
florish.

[pelikhan]

The campaign should probably be a markdown file itself so that we can infuse agentic level behavior.

[mnkiefer]

@pelikhan: This is what I'm envisioning for (enterprise) campaigns. Let me know what you think! 🙏🏼

[pelikhan]

@copilot

• move campaign code to pkg/campaign package
• split campaign.go to small files
• add extensive tests

[Copilot]

@pelikhan I've opened a new pull request, #6136, to work on those changes. Once the pull request is ready, I'll request review from you.

[pelikhan]

Use -, not _ in yaml names

[pelikhan]

Mark as "experimental" so that you can break/iterate