Generate a directory for blueprints at build time

## Guidance
- Modification build.rs

If you write a process similar to the dist directory, it will work.

Start in build.rs and inspect how the dist directory is handled. Use that process as the guide for generating the blueprints directory at build time, then verify the expected directory is produced during the build. The issue does not name a test or specify the generated contents, so confirm those expectations from the existing dist-directory logic.

Written by the indexing model from the issue text.