Launch hardening: remaining P0 gates

The gate list between today and public launch, from docs/roadmap/launch-blockers.md (reconciled 2026-07-04/05):

Testing depth

• Journey E2E for the six uncovered flows: forms, tasks, messaging, billing, e-sign, notifications (13 specs exist and gate CI/deploy today; WS-14 tracks the rebuild).
• Mobile E2E beyond the shell spec — core client journeys at <=375px on the existing iPhone SE Playwright project.

Observability (code done, owner provisioning open)

• Provision an error-tracking DSN (Sentry/GlitchTip, runbook: error-tracking-setup.md), deploy the Uptime-Kuma monitor, then trigger one real captured error.

Release ops

• Rollback exercised once for real; post-deploy boot smoke test; backups shipped off-host + bucket versioning (backup-restore runbook §6).

Contracts

• Move the four remaining Draft contracts to Approved: observability, messaging, tasks, engagements.

Vendor remainders (deploy-gated)

• Cal.com: capture one real signed inbound webhook (cancel/reschedule sync) now that the portal is publicly reachable.
• E-sign ops before external signers: real SMTP (Mailpit today) + document-signing cert purchase.