feat(gateway): add configurable lane queue mode, cap, and overflow

src/gateway/server.ts

@@ -6,6 +6,7 @@ import { serveStatic } from './static.js';
 import { SessionBridge } from './session-bridge.js';
 import type { SessionBridgeConfig } from './session-bridge.js';
 import { LaneQueue } from './lane-queue.js';
+import type { LaneQueueConfig } from './lane-queue.js';
 import { MetricsCollector } from './metrics.js';
 import { authenticateRequest } from './auth.js';
 import type { AuthConfig } from './auth.js';
@@ -84,6 +85,7 @@ export interface GatewayServerConfig {
     maxViolations?: number;
     violationWindowMs?: number;
   };
+  queue?: Partial<LaneQueueConfig>;
   /** Optional pairing manager for DM pairing code management via gateway. */
   pairingManager?: PairingManager;
   memoryStore?: MemoryStore;
@@ -143,7 +145,7 @@ export class GatewayServer {
       memoryStore: config.memoryStore,
     });
 
-    this.laneQueue = new LaneQueue();
+    this.laneQueue = new LaneQueue(config.queue);
     this.metrics = new MetricsCollector({
       getQueueDepth: () => this.laneQueue.totalPending(),
     });