[feature Request] High fee warning

I think it would be cool if the Hardware Wallet would warn you. If you are about to make a transaction with a disproportionate high transaction fee.

Maybe something like:
more than 20% of the amount with transactions above 100 000 sats
more than 30% of the amount with transactions under 100 000 sats

And maybe a relative amount if sats/vbyte is very high.

Maybe like 100 sats per vbyte -> warning high fee

300 sats per vbyte -> warning very high fee

I think this could protect users from accidently signing a transaction with to high transaction fees.

P.S.
Maybe it would be cool to have the sats/vbyte rate displayed at the hardware Wallet as well. Maybe in the advanced settings. (if this could be easily implemented)

The issue names no files or tests. Start by tracing the hardware wallet's transaction-signing flow and any existing fee or sats-per-vbyte display, then clarify which warning thresholds and display changes are required. Done means the agreed high-fee cases are detected before signing and the resulting warning behavior is covered by tests.

Written by the indexing model from the issue text.