Martian Football: the second scenario is playable

The setup menu gains a SCENARIO group. Picking Football relayouts the
menu live: the track list swaps to the football-legal set (drops
Paingod Passage and the race build of Freezemoon Freeway, adds the
football build headmf - RPConfig per-scenario invalid lists), the
COLOR and BADGE columns become TEAM and POSITION, and the title
reads MARTIAN FOOTBALL.

The egg builder was restructured around one flat pilot table so both
scenarios share it. Football emits scenario=football, per-pilot team=
and position= entries, and the [teams] / [team::X] / [pilots::X] /
[teambitmap] blocks in RPFootballMission layout (team name bitmaps
generated by the same GDI plasma renderer as pilot names). Colors are
derived rather than chosen, as the arcade did it: the runner wears the
team runner color, crushers and blockers the team color. Multi-pod
games alternate pilots across two teams and give each team exactly one
runner, honoring the host own position pick.

Verified end to end: Football launches from the menu, the engine loads
the football mission (the cockpit shows the RUNNER - GO FOR POINTS
panel), the console marshals it to a scored finish, and the Death Race
path still passes its regression unchanged.

Known gap: lobby members cannot pick their own team or position yet -
the host pick seeds a deterministic assignment.

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

README.md

@@ -1,8 +1,8 @@
 # Red Planet 4.12 — the Steamification
 
-**Red Planet** is VWE's pod-racing game: eight-player VTV races on Mars,
-originally played from inside VWE Tesla cockpit pods. This repo is the
-third life of that code:
+**Red Planet** is VWE's pod-racing game: eight-player VTV contests on Mars
+— **Martian Death Race** and **Martian Football** — originally played from
+inside VWE Tesla cockpit pods. This repo is the third life of that code:
 
 | Generation | What it was |
 |------------|-------------|
@@ -34,8 +34,9 @@ lobby.
 ## Playing
 
 Grab the release zip (or run `pack-dist.ps1` on a build). Single player:
-run `start-windowed.bat` — the game boots into the race setup menu. Steam
-multiplayer: see
+run `start-windowed.bat` — the game boots into the setup menu, where the
+SCENARIO group picks Death Race or Football (Football swaps in the
+team/position columns and its own track list). Steam multiplayer: see
 [docs/STEAM-3-MACHINE-TEST.md](docs/STEAM-3-MACHINE-TEST.md) (until RP412
 has its own AppID it runs under Spacewar, 480).