Delete an AI Gateway provider

Requires ai_gateway_config_write and provider Edit. Models and pricing inherit provider access. This also applies when force=true. Existing cascades remain and can affect policies the caller cannot edit. Delete a provider by ID. Providers used by routing rules return provider_in_use with HTTP 409 and the affected rules in error metadata. Retry with force=true to remove provider targets and delete rules left without targets. Surviving tiers keep their ordering and weights. A deletion that would rewrite a surviving tier with an unknown ordering_issue fails with HTTP 409 and code routing_rule_unknown_ordering until that rule is replaced or deleted.