Happy path UI buttons are not autofocused

### Steps to reproduce

The most common UI button should be focused by default so you can hit enter to rapidly select it
* Join button when entering a call
* Submit button when rageshaking (not the close button)
* probably others

### Outcome

#### What did you expect?
default focus on happy case UI flow

#### What happened instead?
no focus, or focus on unhappy case flows

### Operating system

_No response_

### Browser information

_No response_

### URL for webapp

call.element.io

### Will you send logs?

No

Reproduce the missing focus behavior at call.element.io for the Join flow and rageshaking submission flow, then trace the relevant TypeScript UI components. Done means the happy-path button is focused by default, Enter activates it, and unhappy-path controls such as Close are not focused instead.

Written by the indexing model from the issue text.