feat: implement user session management with Redis and add game token verification

app/gateway-api/src/config.ts

@@ -3,8 +3,10 @@ export interface GatewayApiConfig {
     port: number;
     trpcPath: string;
     redisKeyPrefix: string;
+    flushChannel: string;
     sessionTtlSeconds: number;
     gameSessionTtlSeconds: number;
+    gameTokenSecret: string;
 }
 
 const parseNumber = (value: string | undefined, fallback: number, label: string): number => {
@@ -21,16 +23,23 @@ const parseNumber = (value: string | undefined, fallback: number, label: string)
 export const resolveGatewayApiConfigFromEnv = (
     env: NodeJS.ProcessEnv = process.env
 ): GatewayApiConfig => {
+    const secret = env.GAME_TOKEN_SECRET ?? env.GATEWAY_TOKEN_SECRET ?? '';
+    if (!secret) {
+        throw new Error('GAME_TOKEN_SECRET is required for gateway token encryption.');
+    }
+    const redisKeyPrefix = env.GATEWAY_REDIS_PREFIX ?? 'sammo:gateway';
     return {
         host: env.GATEWAY_API_HOST ?? '0.0.0.0',
         port: parseNumber(env.GATEWAY_API_PORT, 13000, 'GATEWAY_API_PORT'),
         trpcPath: env.TRPC_PATH ?? '/trpc',
-        redisKeyPrefix: env.GATEWAY_REDIS_PREFIX ?? 'sammo:gateway',
+        redisKeyPrefix,
+        flushChannel: `${redisKeyPrefix}:flush`,
         sessionTtlSeconds: parseNumber(env.SESSION_TTL_SECONDS, 60 * 60 * 24 * 7, 'SESSION_TTL_SECONDS'),
         gameSessionTtlSeconds: parseNumber(
             env.GAME_SESSION_TTL_SECONDS,
             60 * 60 * 6,
             'GAME_SESSION_TTL_SECONDS'
         ),
+        gameTokenSecret: secret,
     };
 };