fix: guard getPageById with pageId check in evaluate_script

When pageIdRouting is true but no pageId is provided, getPageById(undefined)
was called which always throws. Mirror the same guard used in index.ts:
only route by pageId when both the flag is on AND a pageId is present.

Author: bcfmtolgahan

src/tools/script.ts

@@ -81,9 +81,10 @@ Example with arguments: \`(el) => {
         return;
       }
 
-      const mcpPage = cliArgs?.pageIdRouting
-        ? context.getPageById(request.params.pageId)
-        : context.getSelectedMcpPage();
+      const mcpPage =
+        cliArgs?.pageIdRouting && request.params.pageId
+          ? context.getPageById(request.params.pageId)
+          : context.getSelectedMcpPage();
       const page: Page = mcpPage.pptrPage;
 
       const args: Array<JSHandle<unknown>> = [];