PostHog product analytics + creator analytics dashboards

Why / Context

PRD §11 defines success metrics per stakeholder (learner completion/pass rates, creator GMV & storefront conversion, mentor utilization/turnaround, platform MRR/take-rate). MVP ships operational dashboards from the DB; this issue adds PostHog product analytics (event funnels, retention, feature flags analysis) and creator-facing analytics dashboards in the studio — the "learner analytics" tooling PRD §6.3 promises creators.

Schema already in place — NO migration required

• DB-side aggregates already computable: Enrollment.progressPct, QuizAttempt, LessonProgress, Order/OrderItem revenue, ProjectReview turnaround, LiveAttendance
• AiUsageEvent / XpEvent provide engagement streams
• No analytics tables added — PostHog is the event store; DB remains source of truth for money

Implementation plan

1. PostHog setup (EU/US cloud choice documented): posthog-js (client, cookieless-by-default until consent) + posthog-node (server events), reverse proxy via Next rewrites to dodge blockers.
2. Event taxonomy (docs/analytics-events.md): signup, activation (first lesson), add_to_cart, checkout_started/paid, subscription_started/churned, lesson_completed, quiz_passed, project_purchased/submitted/passed, storefront_viewed, review_left — server-emitted where money is involved.
3. Identity: alias anonymous → user on login; group analytics by tenant (creator) and org (enterprise).
4. Core funnels & dashboards in PostHog: visitor→signup→activation→purchase; storefront→course-detail→cart→paid (per-tenant breakdown); subscription upgrade paths.
5. Creator analytics in studio (/studio/analytics, server-rendered from DB with PostHog embeds where useful): revenue over time, top content, storefront conversion, learner progress distribution, cohort attendance, review ratings.
6. Mentor ops dashboard (admin): utilization vs capacity, turnaround vs SLA (ProjectReview.turnaroundTargetAt), first-pass agreement rate.
7. Consent: cookie banner gating client capture (ties to issue #24), server events unaffected (legitimate interest documented).
8. Weekly metrics digest email to platform admins (Novu, issue #10).

Acceptance criteria

• End-to-end purchase funnel visible in PostHog with per-tenant breakdown
• Creator sees revenue, conversion, and engagement for their own tenant only
• Money numbers on creator dashboards reconcile with ledger (DB-sourced, not PostHog)
• Consent banner blocks client capture until accepted
• Mentor SLA dashboard flags overdue reviews

Dependencies / sequencing

• MVP M7–M10 provide the events; issue #10 for digests
• Feeds pricing/packaging decisions (PRD §8.3 says move prices on real willingness-to-pay data)

Start with the implementation plan, docs/analytics-events.md, the /studio/analytics entry point, and the existing DB models listed in the issue. Review dependencies on issue #10 and issue #24 before deciding the integration boundaries. Done means the listed funnels, tenant-scoped creator metrics, consent behavior, ledger reconciliation, and mentor SLA flags meet the acceptance criteria.