feat(stdlib): new modules + eslint/tsconfig migration

- Add array/async/etc. modules and type tests; migrate to eslint flat config
  and composite tsconfig (vitest typecheck enabled).
- Fix PubSub.emit to snapshot listeners before iterating (stable EventEmitter
  semantics; avoids invoking listeners added during the same emit).

core/stdlib/src/structs/Deque/index.test.ts

@@ -1,4 +1,4 @@
-import { describe, it, expect } from 'vitest';
+import { describe, expect, it } from 'vitest';
 import { Deque } from '.';
 
 describe('deque', () => {
@@ -31,6 +31,22 @@ describe('deque', () => {
       expect(deque.length).toBe(0);
       expect(deque.isFull).toBe(false);
     });
+
+    it('throw when initial values exceed maxSize', () => {
+      expect(() => new Deque([1, 2, 3, 4, 5], { maxSize: 3 })).toThrow(RangeError);
+    });
+
+    it('enforce maxSize against subsequent pushes', () => {
+      const deque = new Deque([1, 2], { maxSize: 2 });
+
+      expect(deque.isFull).toBe(true);
+      expect(() => deque.pushBack(3)).toThrow(RangeError);
+      expect(() => deque.pushFront(0)).toThrow(RangeError);
+
+      deque.popFront();
+      expect(deque.isFull).toBe(false);
+      expect(() => deque.pushBack(3)).not.toThrow();
+    });
   });
 
   describe('pushBack', () => {