chore: finish zero-swarm cleanup and refresh World Lab docs

[christopherjnelson]

Pre-swarm screenshots, chat styling, and social-message test fixtures remained after the zero-swarm migration. This cleanup removes those remnants and refreshes the README with the current operator workflow, real scripted-mode screenshots, and CI/toolchain badges.

• Remove unused chat, per-agent override, and legacy turn/observation styles; rename activity-dock state while preserving stored preferences, and remove obsolete message counters and duplicate model-option assertions.
• Preserve archive upgrade migrations, retirement guards, deterministic ablation controls, and historical ADR decision bodies. Clarify superseded statuses and current planning and trust boundaries.
• Switch to standard OpenStreetMap tiles with a dark MapLibre raster treatment and visible attribution. No basemap key is required. Browser smoke tests use a local tile image fixture so CI does not contact the public tile service.
• Ignore local agent workspace metadata and replace outdated screenshots with current Live and Agents captures.

The repository owner confirmed final local validation was all green, including pnpm validate and pnpm test:e2e. Agents did not run local validation. Screenshots were captured against the explicitly scripted local application without real model-provider calls.