chainparams: add assumeutxo snapshot at height 976000 - #444

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/cache/restore@v4. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

`$HOMEBREW_NO_INSTALLED_DEPENDENTS_CHECK` is set: not checking for outdated dependents or dependents with broken linkage!

qt@5 has been deprecated because it is not supported upstream! It will be disabled on 2027-05-19.

Ccache hit-rate in ci_mac_native_fuzz was 0.00%