Hold QR animation on brightness tips and reset animated QR sequence

[kdmukai]

Depends on #494

This PR actually only has minimal changes; to get a proper diff you need to compare against https://github.com/kdmukai/seedsigner/tree/qr_encoding_refactor

Description

For fountain encoders, the first n frames are extremely valuable. But since we start the animated QR sequence with the brightness tip overlaid, many of the early frames will be wasted and/or unreadable.

This change pauses the current frame whenever the brightness tip is visible and then restarts the animated QR sequence (per @jdlcdl's suggestion) when the brightness tip deactivates.

Fountain encoders: should be beneficial
"Simple" animated encoders (Specter xpub): doesn't really matter
Static encoders: no effect

This pull request is categorized as a:

• New feature (really a behavior change)

Checklist

• I’ve run pytest and made sure all unit tests pass before sumbitting the PR

If you modified or added functionality/workflow, did you add new unit tests?

• N/A

If this evolves to support more elaborate changes to the fountain encoder sequence, then dedicated tests will be added.

I have tested this PR on the following platforms/os:

• Raspberry Pi OS Manual Build
• SeedSigner OS on a Pi0/Pi0W board

Note: Keep your changes limited in scope; if you uncover other issues or improvements along the way, ideally submit those as a separate PR. The more complicated the PR the harder to review, test, and merge.

[jdlcdl]

ACK tested as of commit 2653c8e

This worked for me, rather nicely especially when late about getting the camera focused on seedsigner screen.
I see all tests passed above, they passed on a linux desktop and also on my rpi0 dev setup.

[newtonick]

ACK and tested without any issues