feat(ioc): add lifecycle visualization lab for class loading and bean scopes

src/main/java/com/example/scaffold/learning/lifecycle/SingletonLifecycleBean.java

@@ -0,0 +1,49 @@
+package com.example.scaffold.learning.lifecycle;
+
+import jakarta.annotation.PostConstruct;
+import jakarta.annotation.PreDestroy;
+import org.springframework.stereotype.Component;
+
+import java.util.LinkedHashMap;
+import java.util.Map;
+import java.util.UUID;
+import java.util.concurrent.atomic.AtomicInteger;
+
+@Component("iocSingletonLifecycleBean")
+public class SingletonLifecycleBean implements LifecycleDemoBean {
+
+    static {
+        IocLifecycleTracker.record("iocSingletonLifecycleBean", "singleton", "class-load", "JVM 初始化类（static block）");
+    }
+
+    private final String instanceId = UUID.randomUUID().toString().substring(0, 8);
+    private final AtomicInteger accessCount = new AtomicInteger(0);
+
+    public SingletonLifecycleBean() {
+        IocLifecycleTracker.record("iocSingletonLifecycleBean", "singleton", "constructor", "构造器执行，实例ID=" + instanceId);
+    }
+
+    @PostConstruct
+    public void init() {
+        IocLifecycleTracker.record("iocSingletonLifecycleBean", "singleton", "post-construct", "Bean 初始化完成，已进入单例生命周期");
+    }
+
+    @PreDestroy
+    public void destroy() {
+        IocLifecycleTracker.record("iocSingletonLifecycleBean", "singleton", "pre-destroy", "容器关闭时销毁单例 Bean");
+    }
+
+    @Override
+    public Map<String, Object> inspect(String trigger) {
+        int count = accessCount.incrementAndGet();
+        IocLifecycleTracker.record("iocSingletonLifecycleBean", "singleton", "method-call", "trigger=" + trigger + ", accessCount=" + count);
+        Map<String, Object> result = new LinkedHashMap<>();
+        result.put("beanName", "iocSingletonLifecycleBean");
+        result.put("scope", "singleton");
+        result.put("instanceId", instanceId);
+        result.put("identityHashCode", System.identityHashCode(this));
+        result.put("accessCount", count);
+        result.put("explanation", "单例 Bean 在容器中通常只创建一次，后续每次获取都是同一个实例");
+        return result;
+    }
+}