fix(entity): update EntityId type parameters for clarity

Author: codehz

src/entity.ts

@@ -17,7 +17,7 @@ declare const __entityIdTypeTag: unique symbol;
  * - Entity IDs: 1024+
  * - Relation IDs: negative numbers encoding component and entity associations
  */
-export type EntityId<T = void, U = unknown> = number & {
+export type EntityId<T = unknown, U = unknown> = number & {
   readonly [__componentTypeMarker]: T;
   readonly [__entityIdTypeTag]: U;
 };

src/world.ts

@@ -157,13 +157,13 @@ export class World {
    * Create a new entity
    * @returns The ID of the newly created entity
    */
-  new(): EntityId {
+  new<T = void>(): EntityId<T> {
     const entityId = this.entityIdManager.allocate();
     // Create empty archetype for entities with no components
     let emptyArchetype = this.ensureArchetype([]);
     emptyArchetype.addEntity(entityId, new Map());
     this.entityToArchetype.set(entityId, emptyArchetype);
-    return entityId;
+    return entityId as EntityId<T>;
   }
 
   /**