fix: Manually trigger GPIO update in File Browser mode (#819)
## Summary
* Manually trigger GPIO update in File Browser mode
* Previously just assumed that the GPIO data would update automatically
(presumably via yield), the data is currently updated in the main loop
(and now here as well during the middle of the processing loop).
* This allows the back button to be correctly detected instead of only
being checked once every 100ms or so for the button state.
## Additional Context
* Fixes
https://github.com/crosspoint-reader/crosspoint-reader/issues/579
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## Summary by CodeRabbit
* **Bug Fixes**
* Enhanced input state detection in the web server interface for more
responsive and accurate user command recognition during high-frequency
operations.
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