fix(a2ui): correct basic catalog id + Composer/Theater URLs

- A2UI_BASIC_CATALOG_ID was a guessed URL; @a2ui/web_core ships it as
  https://a2ui.org/specification/v0_9/basic_catalog.json. Mismatched id
  caused @a2ui/lit's MessageProcessor to throw "Catalog not found"
  inside the live render column.
- A2UI Composer/Theater are hosted at a2ui-composer.ag-ui.com, not
  a2ui.org/{composer,theater}. The Theater path on a2ui.org 404s.

Author: mirkokiefer

gallery/build.ts

@@ -472,8 +472,8 @@ const cardHtml = (c: Card) => {
         <div class="open-in" data-open-in>
           <button data-action="copy-a2ui" data-jsonl="${escapeHtml(medium.a2ui)}">Copy A2UI JSONL</button>
           <button data-action="copy-json" data-json="${escapeHtml(medium.json)}">Copy WidgetData JSON</button>
-          <a href="https://a2ui.org/composer" target="_blank" rel="noreferrer noopener">Open in A2UI Composer ↗</a>
-          <a href="https://a2ui.org/theater" target="_blank" rel="noreferrer noopener">A2UI Theater ↗</a>
+          <a href="https://a2ui-composer.ag-ui.com/" target="_blank" rel="noreferrer noopener">Open in A2UI Composer ↗</a>
+          <a href="https://a2ui-composer.ag-ui.com/theater" target="_blank" rel="noreferrer noopener">A2UI Theater ↗</a>
           <a href="https://docs.openclaw.ai/platforms/mac/canvas" target="_blank" rel="noreferrer noopener">OpenClaw Canvas ↗</a>
           <a href="https://github.com/CopilotKit/generative-ui-playground" target="_blank" rel="noreferrer noopener">CopilotKit Playground ↗</a>
         </div>