feat: add conditional free-user onboarding - #2277

Adds a six-email onboarding journey with follow-ups based on completed cloud recordings and sharing signals. Eligible new free accounts receive a persistent assignment; purchases, unsubscribes, teammate exclusions, and imported-contact holds remain respected.

Enrollment requires an explicit flag and signup boundary. The workflow is included in delivery checks, and emails/onboarding-runtime.md documents configuration, signal limitations, and rollback.

Validation: 81 email/routing/consent/watchdog tests, 10 read-only SQL fixture tests, scoped TypeScript and formatting checks, and browser review of all six Loops emails. No schema migration.

Confidence Score: 5/5

The PR appears safe to merge, with experiment enrollment disabled unless explicitly configured and no actionable defects found in the reviewed paths.

Summary

• Uses deterministic user bucketing and preserves assignments across subsequent lifecycle changes.
• Introduces stricter cloud-video activation signals and hourly synchronization for experiment follow-ups.
• Adds workflow provisioning, verification, watchdog coverage, email definitions, and experiment measurement guidance.
• No actionable correctness, security, or repository-rule violations were identified.

_{Reviews (1) · Last reviewed commit: "feat: test activation-led Pro onboarding..."}