fix(cypress): use retry-able cy.get for audio setup button in stepVideoCheck

The synchronous $body.find() check raced against React rendering — after
VideoEquipmentCheck auto-passes, AudioEquipmentCheck needs a render cycle
to mount its "Begin audio setup" button. Replace with cy.get() which
retries until the button appears (up to 10s).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: JamesPHoughton

cypress/support/sharedSteps.js

@@ -196,11 +196,11 @@ Cypress.Commands.add(
 
     if (setupMicrophone || setupHeadphones) {
       const audioButton = `[data-player-id="${playerKey}"] button[data-test="startAudioSetup"]`;
-      cy.get("body").then(($body) => {
-        if ($body.find(audioButton).length > 0) {
-          cy.get(audioButton).should("be.visible").click();
-        }
-      });
+      // Use cy.get with retry instead of synchronous $body.find(), because
+      // the audio setup button may not have rendered yet when the video check
+      // auto-completes (the Cypress window.Cypress shortcut advances the
+      // intro step, and React needs a render cycle to mount AudioEquipmentCheck).
+      cy.get(audioButton, { timeout: 10000 }).should("be.visible").click();
     }
   }
 );