fix: broken reproducibility

[gilcu3]

Closes #1932

The cluprit seems to have been a mix of jemalloc and the built crate. The jemalloc part was fixed in #1935. Would be nice to add it back

I got repro with this branch, locally:

commit hash: d56d8f112796d582aaf39923bce55f184b0cca70
SOURCE_DATE_EPOCH used: 0
node binary hash: 7bcec996bac31018387d166397815a364d07416a1dfbe703e39a667b6d2adc56
node docker image hash: sha256:24f18b462ac770a3701f84a34eff8fc4470abf15c4bb2291ed1537d9e470fd5e

and in CI https://github.com/near/mpc/actions/runs/21820809884/job/62953357578

added also a nit, as we are using/testing claude locally we should ignore the local config folder

This is the TL;DR of the fix:

The built crate generates ~20 constants via include!(), and we only use 4 of them. The unused ones still end up in the binary (they were pub const in a pub mod), and some would differ between local and CI (why this was not happening before is a mystery, but hopefully now we are more robust):

• GIT_HEAD_REF: Locally Some("refs/heads/main"), in CI (detached HEAD from actions/checkout) it's None. Different string lengths → different .rodata layout.

These unused but still-present constants apparently shifted the positions of stuff in .rodata., obtained with:

readelf --wide --decompress --hex-dump=.rodata target/reproducible/mpc-node

[barakeinav1]

thank you!