feat(cli): add manage action group and update skills for plan awareness [AI-72]

[thebiglabasky]

Summary

• Adds a new manage action group to the skills system with plan reference for account entitlements
• Updates existing skills references to catch up with recent CLI additions
• Teaches agents to check the account plan before configuring checks (prevents unauthorized feature usage)

New content

• manage.md — action group overview: plan-aware workflow, guidance to check entitlements before writing checks
• manage-plan.md — account plan command reference: usage examples, abbreviated JSON response shape, practical patterns for filtering locations and respecting limits

Updated content

• skill.md — new "Plan Awareness" section explaining upgrade links (checkout + contact sales)
• initialize.md — new Step 3 "Check your account plan" before creating config, with guidance to only use available locations and enabled features
• configure.md — replaced vague "Check Locations and Plan Tiers" section with precise pointer to account plan --output json
• investigate-checks.md — added checks stats command (merged in feat(cli): add checks stats command #1256, was missing from skills)
• communicate-incidents.md — added status-pages get command (merged in fix: globalSetup, globalTeardown and tsconfig files from Playwright config are detected again #1250, was missing from skills)
• context.ts — registered MANAGE_REFERENCES and manage action

Why

From AI-60: agents were using enterprise-only features (locations, retry strategies) without knowing the subscription tier. This update ensures agents discover checkly account plan early in their workflow and use it to scope their work to what the plan supports. Disabled features include upgrade URLs so agents can proactively suggest upgrades.

Test plan

• TypeScript compiles clean
• 124 tests passing (command metadata + skills install)
• npm run prepare generates manage references in dist/ai-context/
• Generated SKILL.md includes manage action group
• No changes to build pipeline (prepare-ai-context.ts handles new action generically)

🤖 Generated with Claude Code

[stefanjudis]

Great stuff. love it.