feat: 重构事件总线为可实例化架构并发布 1.3.0

- 新增 IShrinkEventBus、ShrinkEventBusBuilder 与 ShrinkEventBusInstance，支持独立 bus、异常策略、启动开关、类型校验和按 phase 派发
- 新增 SubscribeEvent 可释放订阅句柄与订阅快照接口，保留 EventBus 静态门面并委托到默认实例
- 重构监听列表为父子事件链共享锁与快照缓存，支持父事件监听子事件、跨父子数字优先级归并和防御性快照拷贝
- 优化 EventBase 元数据缓存、懒生成 EventId、派发快照挂接与对象池双重归还保护，移除旧 EventCache 热路径
- 恢复本地 ILPostProcessor 兜底并生成静态订阅注册表，避免共享 CodeGen 覆盖外程序集自动注册失效
- 改进事件查看器、Benchmark、README 与 CHANGELOG，并新增 Dispatch/Priority/Registration/Subscription 测试覆盖核心行为

BREAKING CHANGE: 移除 EventBase.GetListenerList()，int 数字优先级重载不再提供默认值，数字优先级 0 现在映射为 NORMAL。

Tests/EventBusPriorityTests.cs

@@ -0,0 +1,120 @@
+using System.Collections.Generic;
+using NUnit.Framework;
+
+namespace ShrinkEventBus.Tests
+{
+    [TestFixture]
+    public sealed class EventBusPriorityTests
+    {
+        private class BaseEvent : EventBase
+        {
+        }
+
+        private sealed class DerivedEvent : BaseEvent
+        {
+        }
+
+        [Test]
+        public void EnumPriority_ExecutesPhasesInOrder()
+        {
+            var bus = EventBus.CreateBus();
+            var order = new List<string>();
+
+            bus.RegisterEvent<BaseEvent>(_ => order.Add("LOW"), EventPriority.LOW);
+            bus.RegisterEvent<BaseEvent>(_ => order.Add("MONITOR"), EventPriority.MONITOR);
+            bus.RegisterEvent<BaseEvent>(_ => order.Add("HIGHEST"), EventPriority.HIGHEST);
+            bus.RegisterEvent<BaseEvent>(_ => order.Add("NORMAL"), EventPriority.NORMAL);
+
+            bus.TriggerEvent(new BaseEvent());
+
+            CollectionAssert.AreEqual(new[] { "HIGHEST", "NORMAL", "LOW", "MONITOR" }, order);
+        }
+
+        [Test]
+        public void NumericPriority_HigherNumberRunsFirstWithinPhase()
+        {
+            var bus = EventBus.CreateBus();
+            var order = new List<string>();
+
+            // 5 与 10 都映射到 NORMAL 档
+            bus.RegisterEvent<BaseEvent>(_ => order.Add("p5"), 5);
+            bus.RegisterEvent<BaseEvent>(_ => order.Add("p10"), 10);
+
+            bus.TriggerEvent(new BaseEvent());
+
+            CollectionAssert.AreEqual(new[] { "p10", "p5" }, order);
+        }
+
+        [Test]
+        public void NumericPriority_TieKeepsRegistrationOrder()
+        {
+            var bus = EventBus.CreateBus();
+            var order = new List<string>();
+
+            bus.RegisterEvent<BaseEvent>(_ => order.Add("first"), 0);
+            bus.RegisterEvent<BaseEvent>(_ => order.Add("second"), 0);
+
+            bus.TriggerEvent(new BaseEvent());
+
+            CollectionAssert.AreEqual(new[] { "first", "second" }, order);
+        }
+
+        [Test]
+        public void NumericPriorityZero_MapsToNormalPhase()
+        {
+            var bus = EventBus.CreateBus();
+            bus.RegisterEvent<BaseEvent>(_ => { }, 0);
+
+            var subscribers = bus.GetEventSubscribers<BaseEvent>();
+
+            Assert.AreEqual(1, subscribers.Length);
+            Assert.AreEqual(EventPriority.NORMAL, subscribers[0].Priority);
+        }
+
+        [Test]
+        public void RegisterEvent_WithoutPriority_ResolvesToNormal()
+        {
+            var bus = EventBus.CreateBus();
+
+            void Handler(BaseEvent evt)
+            {
+            }
+
+            // 不带优先级的调用应唯一解析到枚举重载（NORMAL），不再有重载二义性
+            bus.RegisterEvent<BaseEvent>(Handler);
+
+            var subscribers = bus.GetEventSubscribers<BaseEvent>();
+            Assert.AreEqual(1, subscribers.Length);
+            Assert.AreEqual(EventPriority.NORMAL, subscribers[0].Priority);
+        }
+
+        [Test]
+        public void ParentAndChildHandlers_MergeByNumericPriorityWithinPhase()
+        {
+            var bus = EventBus.CreateBus();
+            var order = new List<string>();
+
+            bus.RegisterEvent<BaseEvent>(_ => order.Add("parent10"), 10);
+            bus.RegisterEvent<DerivedEvent>(_ => order.Add("child5"), 5);
+            bus.RegisterEvent<DerivedEvent>(_ => order.Add("child1"), 1);
+
+            bus.TriggerEvent(new DerivedEvent());
+
+            CollectionAssert.AreEqual(new[] { "parent10", "child5", "child1" }, order);
+        }
+
+        [Test]
+        public void ParentAndChildHandlers_TiePrefersChild()
+        {
+            var bus = EventBus.CreateBus();
+            var order = new List<string>();
+
+            bus.RegisterEvent<BaseEvent>(_ => order.Add("parent0"), 0);
+            bus.RegisterEvent<DerivedEvent>(_ => order.Add("child0"), 0);
+
+            bus.TriggerEvent(new DerivedEvent());
+
+            CollectionAssert.AreEqual(new[] { "child0", "parent0" }, order);
+        }
+    }
+}