v2.1.1

Patch release for Subgeneratorr web/runtime deployment fixes.

Highlights:

• Fixes DEFAULT_MODEL handling so configured web defaults are honored end-to-end
• Adds PUID/PGID runtime support for web and worker containers on Linux/NAS deployments
• Clarifies reverse-proxy auth header requirements for protected deployments
• Fixes contributor setup docs and adds regression coverage for runtime default-model behavior