Move the source-code and build platform onto solid-state storage

The platform ran from an SD card, where sustained write latency averaged 8.1 ms and made every repository operation slow.

It now runs on solid-state storage on newer hardware. Measured after the move:

• write latency 8.1 ms to 2.44 ms
• sequential write 35.6 MB/s to 326 MB/s
• a fresh repository clone completes in about a second

The address did not change and the interruption lasted three and a half minutes. The previous machine was kept intact as a rollback.