feat(task): replace built-in task adaptors with a sandboxed JS plugin system (#7076)

types/task_artifact.go

@@ -0,0 +1,9 @@
+package types
+
+// TaskArtifact is the transport-neutral identity of one generated task output.
+// relay/channel re-exports this type for adaptor compatibility.
+type TaskArtifact struct {
+	Key      string `json:"key"`
+	Type     string `json:"type"`
+	MimeType string `json:"mimeType,omitempty"`
+}