Reset a tenant back to a de-novo, never-provisioned state -- admin/ops tool for re-testing signup/provisioning against the same account without a full (irreversible) account deletion + re-signup cycle each time.

Drops the tenant's own customer database (never the whole shared pool project -- see hosted.reset_tenant_provisioning's docstring), clears its Neon provisioning fields, and force-logs-out every existing session/API token for that tenant. The tenant row itself, its email, plan, and Stripe subscription are all left untouched -- this is NOT delete_account (routes/export.py), which is permanent.

Requires an explicit {"confirm": true} body, matching admin_restart's own confirmation pattern above.