feat(framework): StoreBinder 响应式视图绑定 mixin

替代 1773 处 set_self 调用的视图端契约:
- bind(store, slot, cb): 首次同步 + 订阅变化
- unbindAll(): 退订全部(幂等,可重复调用)
- callback 抛错隔离:首次同步与后续订阅均不污染 binder 状态

设计为 mixin 而非 cc.Component 子类:
- 单测不依赖 cc(纯逻辑)
- 业务侧自由组合 cc.Component + binder
- 单一职责:StoreBinder 只管订阅,Component 管生命周期

135/135 tests pass, typecheck exit 0。

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

cocoscreator_projects/framework-tests/ui/store-binder.test.ts

@@ -0,0 +1,92 @@
+import { test } from 'node:test';
+import assert from 'node:assert/strict';
+import { createStoreBinder } from '../../YouleNexus/assets/framework/ui/store-binder.ts';
+import { signal } from '../../YouleNexus/assets/framework/core/reactive.ts';
+
+test('createStoreBinder.bind: 订阅 store 后,值变化时 callback 触发', () => {
+  const store = signal({ name: 'init' });
+  const b = createStoreBinder();
+  let got: string | null = null;
+  b.bind(store, 'state', (s) => { got = s.name; });
+  assert.equal(got, 'init', '首次同步调用一次');
+  store.value = { name: 'changed' };
+  assert.equal(got, 'changed');
+});
+
+test('createStoreBinder.bind: 不同 slot 独立', () => {
+  const store1 = signal(1);
+  const store2 = signal('x');
+  const b = createStoreBinder();
+  const got: Array<number | string> = [];
+  b.bind(store1, 'a', (v) => got.push(v));
+  b.bind(store2, 'b', (v) => got.push(v));
+  assert.deepEqual(got, [1, 'x']);
+  got.length = 0;
+  store1.value = 2;
+  assert.deepEqual(got, [2]);
+});
+
+test('createStoreBinder.unbindAll: 退订后 store 变化不再触发 callback', () => {
+  const store = signal({ x: 0 });
+  const b = createStoreBinder();
+  let count = 0;
+  b.bind(store, 'state', () => { count++; });
+  assert.equal(count, 1);
+  store.value = { x: 1 };
+  assert.equal(count, 2);
+  b.unbindAll();
+  store.value = { x: 2 };
+  assert.equal(count, 2, '退订后不再触发');
+});
+
+test('createStoreBinder: 多次 bind 的 unbindAll 全部退订', () => {
+  const a = signal(1);
+  const b = signal(2);
+  const binder = createStoreBinder();
+  let na = 0, nb = 0;
+  binder.bind(a, 'a', () => na++);
+  binder.bind(b, 'b', () => nb++);
+  assert.equal(na, 1);
+  assert.equal(nb, 1);
+  binder.unbindAll();
+  a.value = 10;
+  b.value = 20;
+  assert.equal(na, 1);
+  assert.equal(nb, 1);
+});
+
+test('createStoreBinder: bind 同一 store 多次,各 callback 都触发', () => {
+  const store = signal(0);
+  const b = createStoreBinder();
+  let a = 0, b2 = 0;
+  b.bind(store, 'x', () => a++);
+  b.bind(store, 'y', () => b2++);
+  assert.equal(a, 1);
+  assert.equal(b2, 1);
+  store.value = 1;
+  assert.equal(a, 2);
+  assert.equal(b2, 2);
+});
+
+test('createStoreBinder.unbindAll: 重复调用安全(幂等)', () => {
+  const store = signal(0);
+  const b = createStoreBinder();
+  let n = 0;
+  b.bind(store, 's', () => n++);
+  b.unbindAll();
+  b.unbindAll(); // 不抛错
+  store.value = 1;
+  assert.equal(n, 1);
+});
+
+test('createStoreBinder.bind: callback 抛错不影响其它订阅者与下次 bind', () => {
+  const store = signal(0);
+  const b = createStoreBinder();
+  let reached = false;
+  b.bind(store, 'a', () => { throw new Error('boom'); });
+  b.bind(store, 'b', () => { reached = true; });
+  // 首次同步调用 + 第二次同步触发都不会让 binder 崩溃
+  assert.equal(reached, true);
+  store.value = 1;
+  assert.equal(reached, true);
+});