Final Hackathon Polish: Left-side dashboard layout, SVG connection scaling, and 0.4s simulation speedup

fix(ui): correct missing return statement in OfficeScene

fix(ui): revert layout crop to stretch scaling, set fast_mode true

fix(ui): correct coordinate drift and text scaling in OfficeScene layout

Hackathon Final Submission: PettingZoo multi-agent arch, GRPO training, docs