[Improved, Fixed] Better microphone permission handling

Improvements

• The start button on the interview tips screen now stays active unless the browser has explicitly blocked the microphone, letting candidates proceed and receive the permission prompt instead of being prematurely stopped. Helpful guidance text appears for users who still need to grant access.

Fixes

• Tapping “Retry” after a microphone denial now refreshes the page, giving candidates who just adjusted their browser settings a second chance to grant access without getting stuck in an endless error loop.