v1.0.21 - Server runtime parity and server-owned ping-pong

Highlights

• Ships the server-authoritative Live Agent Mode runtime stack with the Colyseus realtime sidecar.
• Adds shared runtime snapshots, route leases, observer buffering, visual state mirroring, and world runtime authority.
• Brings server-owned agents closer to the 8590/8595 behavior baseline with collision routing, route smoothing, door repair, queue coordinate fixes, route watchdogs, social conversations, desk fallback, object orientation fixes, armchair/dismount handling, and runtime cleanup.
• Moves ping-pong fully to server-pingpong-runtime, including server-owned pairing, ball/score state, player leases, cooldowns, stale cleanup, browser read-only rendering, and clean result/dismount transitions.
• Makes the Docker install product-ready by starting both virtual-world and virtual-world-realtime, documenting private port 8591, and removing PR-specific cache keys.

Verification

• Product smoke suite passed on GitHub.
• Fresh PR #59 GitHub checkout was tested locally before merge with smoke, realtime, collision, door, route, queue, watchdog, social, Python compile, Docker Compose, Docker build, and live 8587/8588 review checks.

Upgrade Notes

• Docker Compose now starts a realtime sidecar service named virtual-world-realtime by default.
• Keep the web port 8590 and realtime sidecar port 8591 private to your machine, LAN, VPN, Tailnet, or authenticated reverse proxy.