RP412: fork from RP411 — Steam + internet-multiplayer line

Consumer port of Red Planet: sellable on Steam, internet multiplayer,
playable without cockpit hardware. Adds the project README and
docs/RP412-ROADMAP.md covering the three workstreams (vRIO-derived
input/display, TeslaConsole-derived session UI, Steamworks networking)
and the Steam logistics assessment.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

README.md

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+# Red Planet 4.12
+
+**Red Planet** is the VWE pod-racing game built on the in-house **MUNGA** engine
+(Win32 / DirectX 9, `MUNGA_L4` platform layer). The **4.12** line is the
+consumer port: a version of Red Planet that can be **sold on Steam** and played
+over **internet multiplayer**, without cockpit-pod hardware.
+
+Forked from [RP411](https://gitea.mysticmachines.com/VWE/RP411.git)
+(the arcade/cockpit 4.11 line) with full history preserved.
+
+## Goals
+
+1. **Steam distribution** — Steamworks integration, SteamPipe builds, store-ready packaging.
+2. **Internet multiplayer** — take the engine's LAN-era WinSock networking online
+   (NAT traversal, matchmaking, latency tolerance).
+3. **No cockpit required** — keyboard / mouse / gamepad input and on-screen
+   replacements for the pod's RIO panel and plasma display, drawing on
+   [vRIO](https://gitea.mysticmachines.com/VWE/VRIO.git).
+4. **Self-hosted sessions** — in-game race setup/join replacing the operator-driven
+   [TeslaConsole](https://gitea.mysticmachines.com/VWE/TeslaSuite.git) flow.
+
+See [docs/RP412-ROADMAP.md](docs/RP412-ROADMAP.md) for the plan and the
+Steam-multiplayer logistics.
+
+## Building
+
+Unchanged from 4.11 for now — see [BUILD.md](BUILD.md)
+(VS 2005/2008 + DirectX SDK June 2010, `Release|Win32`, output `Release\rpl4opt.exe`).
+Toolchain modernization is a roadmap item.
+
+## Related repositories
+
+| Repo | Role |
+|------|------|
+| [RP411](https://gitea.mysticmachines.com/VWE/RP411.git) | Upstream arcade source (this repo's base) |
+| [VRIO](https://gitea.mysticmachines.com/VWE/VRIO.git) | Virtual RIO panel + vPLASMA display — input bindings and display emulation to fold in |
+| [TeslaSuite](https://gitea.mysticmachines.com/VWE/TeslaSuite.git) | TeslaConsole / Launcher / vPOD — the arcade session-control stack 4.12 replaces (and a reference for the Munga control protocol, TCP 1501) |