add support for custom colors (#2103)

## Description:

Added a colors tab in territory patterns modal so players can select
their color.

Refactored the PrivilegeChecker, removed custom flag checks since we no
longer support custom flags.

<img width="479" height="345" alt="Screenshot 2025-09-27 at 5 01 17 PM"
src="https://github.com/user-attachments/assets/ad96da65-f0eb-4731-a861-e6e5fcb4566a"
/>
## Please complete the following:

- [x] I have added screenshots for all UI updates
- [x] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [x] I have added relevant tests to the test directory
- [x] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced

## Please put your Discord username so you can be contacted if a bug or
regression is found:

evan

src/client/ClientGameRunner.ts

@@ -5,7 +5,7 @@ import {
   GameID,
   GameRecord,
   GameStartInfo,
-  PlayerPattern,
+  PlayerCosmeticRefs,
   PlayerRecord,
   ServerMessage,
 } from "../core/Schemas";
@@ -51,8 +51,7 @@ import SoundManager from "./sound/SoundManager";
 
 export interface LobbyConfig {
   serverConfig: ServerConfig;
-  pattern: PlayerPattern | undefined;
-  flag: string;
+  cosmetics: PlayerCosmeticRefs;
   playerName: string;
   clientID: ClientID;
   gameID: GameID;