Update ROADMAP.md to check off four installation/test checklist items: Clean install test, Mod Organizer 2 install test, Second-machine install test, and Steam Deck or LAN client test package.
Replace the phase-based ROADMAP.md with a vertical-slice focused "Commonwealth Online Roadmap" that documents current status (Working Internal Vertical Slice) and the new playable slices (Same-Cell Foundation, Multiplayer Menu, Player State/Animation MVP, World-State Sync, Internal Playtest Package, Small Session, Gameplay Experiments, and later items). The previous Phase 0-6 plan is preserved verbatim in docs/ROADMAP_2026_06_Initial.md for archival reference. The change pivots tracking from low-level bootstrap tasks to playable vertical slices and highlights completed internal milestones and remaining tests.
andrew