Run Artifact Operation

Generic operation-dispatch endpoint.

Dispatches the operation declared in the artifact's type.json operations.{op_name} block through operation_dispatcher.dispatch.

Reserved op names (create, read, update, delete, add, search) are handled by their dedicated CRUD routes above and are not accepted here. invoke is accepted here — it carries an extra body-merge pass (workspace_id / artifacts / resources binding injection) that the dispatched handler can consume; see _build_invoke_dispatch_body.

The dispatcher enforces the grant check (requires_grant), runs the declared handler (dispatch.kind), and emits every event in operations.{op_name}.emits around the call.