Billing suspension & service access

When an organization leaves the paid window and passes the configured grace period without settling the subscription line, billing status becomes OVERDUE. In that state Linkit applies a full service suspension:

• HTTP APIs for authenticated tenant users return 403 Forbidden with body code: BILLING_SERVICE_SUSPENDED, except for payment, authentication, health, webhooks, and contract download routes.
• Admin dashboard shows a blocking overlay; only the Payment and Legal contract flows remain reachable until billing is healthy again.
• Scheduled integration runs for the organization are skipped.
• Manual integration runs (POST /api/v1/integrations/.../execute and batch execute) are rejected with 403.
• Installed integrations are auto-paused (is_active = false) and marked with billing_frozen. They cannot be switched back on from the UI until balances are cleared and the server clears the freeze after a successful payment.

Operational state is also exposed on GET /api/v1/payments/status as service_operational (inverse of hard suspension) together with billing_mode, included_app_slots, and add-on subtotals for transparency.

Suspension checks may be cached briefly per organization; after a successful payment, allow/deny state catches up automatically.