Allow printing longer labels

[sabeechen]

Includes both UI and firmware changes to support printing longer labels, up to ~250 characters.

• Website label textbox scrolls to accommodate longer text. Some visual tweaks are used to make this more convenient (anchoring scroll to borders, "scroll tips" that jump to and indicate label edges)
• E-TKT oled scrolls to print longer labels and adds visual indicators for when the label bleeds off the screen.
• E-TKT label music speeds up for longer labels into a dramatic crescendo befitting the girthy grandeur of your hefty labels.

Additionally, there are some enhancements that kind of came along for the ride:

• Supported emoji render on the e-tkt oled.
• Pressing enter in the label textbox starts a print.
• Mobile keyboards show a "Send" button when editing a label.
• Web app start-up animation has a little more "ker-chunk".
• Web app printing progress locks to character positions.

[andreisperid]

Nice job @sabeechen !

[sabeechen]

Thanks for all the help!