Project creatortrack app playbook

Justin flagged that the Scheduling app build missed platform conventions other CT apps have (sidebar, breadcrumbs, cockpit, onboarding, etc.) because those conventions existed only implicitly in the codebase, never written down. Fix: ~/creatortrack/docs/APP-PLAYBOOK.md was created (commit 302ad07 on feat/scheduling, not yet on main) by auditing polished apps (Sales CRM, Campaigns, Tasks) to extract the full anatomy of a complete app.

Structure: Sections 0-6 cover archetype choice (route app vs system app vs hybrid), catalog entry, install/sidebar wiring, in-app chrome, API/data conventions, quality gates. Section 7 is a cross-cutting registrations table (activity feed, notifications, automations, cockpit, onboarding, help, analytics, quick-new, search, dashboard) that every app must wire or explicitly mark out-of-scope. Includes a shared-vocabulary glossary (route app, ws-scoped, thin redirect, shell, second rail, SidePeek, quick-new, etc.) and a Known Gaps ledger.

Why: prevents future app builds (worker-driven or otherwise) from silently omitting platform integration points; gives Justin and Claude a shared vocabulary for specifying app shape in task briefs.

How to apply: before building or reviewing any CreatorTrack app, read APP-PLAYBOOK.md first and diff the result against the Section 7 table. Any newly discovered convention gap gets appended to the playbook in the same commit that fixes it. /dev-queue briefs must cite it. This is already referenced in [[reference_creatortrack_app_playbook]] if that topic file exists, or should be cross-linked once it does.

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