Prevent numeric input truncation on 32 bit Android

Several exported u64 inputs are converted to usize with `as`, silently truncating values above u32::MAX in packaged 32 bit Android artifacts.

(bdk-android documents 32 bit architectures as unsupported but still packages armeabi-v7a, so this could be p simple)

Locate the exported u64 inputs that are converted to usize with `as`, then inspect how they are packaged for 32-bit Android, particularly armeabi-v7a. Reproduce values above u32::MAX and verify that the resulting Android artifacts preserve the full input value without truncation.

Written by the indexing model from the issue text.