chore: add TypeScript declaration for ZenUml module

Author: MrCoder

packages/mermaid-zenuml/src/zenuml.d.ts

@@ -0,0 +1,11 @@
+declare module '@zenuml/core' {
+  interface RenderOptions {
+    theme?: string;
+    mode?: string;
+  }
+
+  export default class ZenUml {
+    constructor(container: Element);
+    render(text: string, options?: RenderOptions): Promise<void>;
+  }
+}