4-Layer Dev Variant

This is a pre-release carried over from a repo split for a quick 4-layer development board production run.

• nerve_pcb_dev-76bec6f.zip is the original repo's KiBot workflow artifact.
• nerve_pcb_dev-0.1.0-alpha.tar.gz and nerve_pcb_dev-0.1.0-alpha.zip are the release files from the original repo itself.

Any additional binaries are from the most recent main branch for README.md purposes.