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

src/config/schema.ts

@@ -32,6 +32,15 @@ const wsRateLimitSchema = z.object({
   violation_window_ms: z.number().min(1000).max(60000).default(10000),
 }).default({});
 
+const laneQueueSchema = z.object({
+  /** Queue behavior for concurrent requests in the same session lane. */
+  mode: z.enum(['collect', 'steer', 'interrupt']).default('collect'),
+  /** Max queued (pending) requests per lane. */
+  cap: z.number().min(1).max(1000).default(50),
+  /** Overflow strategy when cap is reached. */
+  overflow: z.enum(['drop_old', 'drop_new']).default('drop_old'),
+}).default({});
+
 const serverDiscoverySchema = z.object({
   /** Enable local-network service discovery (mDNS/Bonjour advertisement). */
   enabled: z.boolean().default(false),
@@ -59,6 +68,8 @@ const serverSchema = z.object({
   max_request_body_bytes: z.number().min(1024).max(10 * 1024 * 1024).default(1_048_576),
   /** Per-connection WebSocket ingress rate limit settings. */
   ws_rate_limit: wsRateLimitSchema,
+  /** Per-session gateway lane queue behavior. */
+  queue: laneQueueSchema,
   /** Optional Bonjour/mDNS advertisement settings. */
   discovery: serverDiscoverySchema,
 });