feat: Stackbit 1248 camera scanner

[stackbitme]

Summary

Added a camera scanner for Stackbit 1248 metal backup plates. It reads the punched dots and decodes the BIP39 words automatically.

Works with both 12 and 24 word mnemonics, and supports standard 1248 and 1248mini plates.

How to use

1. Go to Load Mnemonic > Via Camera > Stackbit 1248
2. Paint the punched dots black and place the plate on a dark surface
3. Point the camera at the plate, align it and click the button to capture
4. Review the words — tap any word to edit if needed
5. Confirm

Test plan

• Test with 12-word mnemonic plate
• Test with 24-word mnemonic plate
• Test word editing after scan
• Test with 1248mini plate

[odudex]

Nice @stackbitme!

To move on, the PR needs several adjusts to pass tests, I would start with format and linting, then you need to add translations, fix existing tests, and create new ones to cover the added feature.

[tadeubas]

Hey @odudex, have you tested the PR first? I think it’s better to review the functionality and implementation upfront. If it looks good, then add tests, otherwise @stackbitme may have to redo them after further changes.