Provider lifecycle

Providers that own HTTP clients, connection pools, subprocesses, or other resources can implement ProviderService and be composed through ProviderLifecycle. Providers start in registration order, and a partial startup failure rolls back already-started providers. Successful shutdown runs in reverse order with the configured per-provider cleanup deadline.

The lifecycle coordinator is application-owned and operates only on providers explicitly supplied before runtime startup. It does not load packages, perform health probes, or expose credentials and provider payloads.