[S3-035] Implement residences and workforce allocation

Accidental duplicate of https://github.com/stacksjs/the-settlers-iii-remake/issues/37, created on 2026-10-22 when an interrupted roadmap publish (the disk filled during the run) could not see the existing issues. Closed without work; track S3-035 in https://github.com/stacksjs/the-settlers-iii-remake/issues/37.