Terminology: BattleTech missions, not races

"Race" is Red Planet's term (it's a racing game) and rode in with the
RPL4LOBBY port. In BattleTech the gameplay unit is a MISSION. Sweep it out
of the front-end / lobby / marshal code + the roadmap and steamification
digest: rename the public API BTLobby_Push/PullRaceResults ->
Push/PullMissionResults, the internal PrimeHostedRace -> PrimeHostedMission,
the deferred marshal InstallNetworkRace -> InstallNetworkMission, and the
user-facing strings ("STEAM MISSION LOBBY", "L A U N C H  M I S S I O N",
"HOST/JOIN STEAM MISSION"). Comments follow. No behavior change; both gates
(default + BT412_STEAM) still build + link clean.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

game/reconstructed/btl4console.cpp

@@ -91,7 +91,7 @@ namespace
 				(GetTickCount() - gStartTick) >= (unsigned long)(gMissionSeconds * 1000))
 			{
 				// The console clock expired: snapshot the final scores (the
-				// game state is still live here), then stop the race exactly
+				// game state is still live here), then stop the mission exactly
 				// as the arcade console did (StopMissionMessage on our pod).
 				DEBUG_STREAM << "[marshal] time expired -- stopping mission\n" << std::flush;
 				SnapshotResults();
@@ -114,7 +114,7 @@ void BTLocalConsole_Install(int mission_seconds)
 	gStartTick      = 0;
 	gWatched        = 0;
 	// Marshaled: the in-process console owns the clock, so a console-loss
-	// (there is none locally) would end the race -- harmless for solo.
+	// (there is none locally) would end the mission -- harmless for solo.
 	gConsoleLossEndsMission = True;
 	gPerFrameHook = &ConsoleTick;
 	DEBUG_STREAM << "[marshal] installed (length " << mission_seconds << "s)\n" << std::flush;