fix: Implement NukeWars gamemode fixes

- Fix NukeWars not being treated as a teams game (always 2 teams)
- Fix building restrictions during/after preparation phase
  * Block only MIRVs completely
  * Block nuclear weapons during preparation phase only
  * Allow all other structures
- Fix transport boat movement rules
  * Allow movement within team territory
  * Block movement into enemy territory
- Add proper preparation phase (180 seconds)
- Ensure combat is primarily through nuclear weapons

Technical changes:
- Add NukeWars to GameMode enum
- Implement preparation phase configuration and timing
- Add team territory checks for transport boats
- Fix building restriction logic for NukeWars mode

src/core/game/Game.ts

@@ -151,6 +151,7 @@ export const isGameType = (value: unknown): value is GameType =>
 export enum GameMode {
   FFA = "Free For All",
   Team = "Team",
+  NukeWars = "Nuke Wars"
 }
 export const isGameMode = (value: unknown): value is GameMode =>
   isEnumValue(GameMode, value);