improve OTA workflow

[brianmathews]

Current state when using OTA (Over the Air) updates:

1. The user needs to know where to get the .BIN file from. It would be helpful if there was a link in the "Firmware Update" section HTML page served by the SOTACAT with a link to the official .BIN found at: https://sotamat.com/wp-content/uploads/SOTACAT-ESP32C3-OTA.bin. Alternatively the link could be to the page where the "Download" button is found: and the advantage of this approach is the user could see a message on the HTML page before clicking the download button. That page would be: https://sotamat.com/sotacat/
2. Once the user downloads the .BIN file to their mobile device, and they click the "Select firmware (.bin) file" button to select their downloaded file, they then click the "Upload Firmware" button. There is no indication that an upload is in progress, nor how long this upload should take. I have clicked the button and didn't know it was working and I exited the screen. We should show a popup giving instructions to wait. Once the upload / update finishes there is a message to the user which is helpful, but it is more important to have a message immediately.

@jeffkowalski

[poynting]

I would second this - I tried OTA for the first time this weekend and on Firefox on Android, the behavior was to jump from the settings page to the CAT page after clicking "Upload Firmware". It was unclear if anything was happening and if I should leave it running or something had failed.