Add a GIF upload warning for max width/height

[Times-Z]

Validate GIF dimensions on selection/upload and show a clear warning if exceeding max allowed size (with configured limits)

Acceptance: warning displayed when limit exceeded, upload blocked or requires confirmation per config

[Electro707]

another idea, rather than limiting the GIF, is to process it client-side and send a resized version down to the device.

Another idea from the above is to, rather than sending a GIF, have the client-side process it down to whatever is convenient for the esp8266 so it doesn't need to device the GIF live on displaying it. But this would be a longer goal as a lot of the internal drawing would have to change, and how it is stored in flash.

[Times-Z]

That could be a very good idea and would indeed allow for a lot of optimization in how GIFs and other formats are handled