Sync the contracts mirror from the core authority

Why: Core PR #26 added the node id/source fields to ts/types.ts (the
single authority); the mirror is regenerated so the sync header and
content match make contracts output exactly (manual edits drift).

Evidence: File generated by the make contracts copy steps; combined
verification in the Dev workspace after re-pinning.

Impact: Header banner plus the already-reviewed id/source fields.

Refs: Core PR #26; Dev task feature/generative-ui-u2

src/contracts.ts

@@ -185,6 +185,9 @@ export type UINodeType =
 
 export interface UINode {
   type: UINodeType;
+  /** Surface 层节点级标注（Generative UI U2）：整页唯一稳定 id 与事实来源标识，旧路径不填。 */
+  id?: string;
+  source?: string[];
   title?: string;
   items?: string[];
   kv?: [string, string][];