Allow canvas image queue concurrency up to 100

lib/canvas/image-task-queue.ts

@@ -19,13 +19,14 @@ interface QueueState {
 }
 
 const DEFAULT_CONCURRENCY = 1;
+const MAX_CONCURRENCY = 100;
 const STALE_RUNNING_MS = 5 * 60 * 1000;
 const queueStateKey = "__canvas_image_task_queue_state__";
 
 function getQueueConcurrency(): number {
   const raw = Number.parseInt(process.env.CANVAS_IMAGE_TASK_CONCURRENCY || "", 10);
   if (Number.isFinite(raw) && raw > 0) {
-    return Math.min(raw, 4);
+    return Math.min(raw, MAX_CONCURRENCY);
   }
   return DEFAULT_CONCURRENCY;
 }