feat: enhance @PostConstruct with order and @Qualifier for fields

- Add value() to @PostConstruct for execution order control
- Allow @Qualifier on fields for use with @Inject
- Sort @PostConstruct methods by inheritance depth then order value

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/main/java/com/imyeyu/inject/BeanScanner.java

@@ -253,22 +253,37 @@ public class BeanScanner {
 	}
 
 	private List<Method> findPostConstructs(Class<?> clazz) {
-		List<Method> methods = new ArrayList<>();
+		// 收集所有 @PostConstruct 方法及其元数据（继承深度、order 值）
+		record PostConstructInfo(Method method, int depth, int order) {}
+		List<PostConstructInfo> collected = new ArrayList<>();
 		Class<?> currentClass = clazz;
+		int depth = 0;
 
 		// 从当前类向上遍历到 Object，收集所有 @PostConstruct 方法
 		while (currentClass != null && currentClass != Object.class) {
+			int currentDepth = depth;
 			for (Method method : currentClass.getDeclaredMethods()) {
 				if (method.isAnnotationPresent(PostConstruct.class)) {
 					if (method.getParameterCount() != 0) {
 						throw new InjectException("@PostConstruct method must have no parameters: %s".formatted(method.getName()));
 					}
-					// 添加到列表头部，确保父类方法先执行
-					methods.addFirst(method);
+					int order = method.getAnnotation(PostConstruct.class).value();
+					collected.add(new PostConstructInfo(method, currentDepth, order));
 				}
 			}
 			currentClass = currentClass.getSuperclass();
+			depth++;
 		}
-		return methods;
+
+		// 先按继承深度降序（父类深度大，先执行），同层级内按 order 升序
+		collected.sort((a, b) -> {
+			int depthCompare = Integer.compare(b.depth, a.depth);
+			if (depthCompare != 0) {
+				return depthCompare;
+			}
+			return Integer.compare(a.order, b.order);
+		});
+
+		return collected.stream().map(PostConstructInfo::method).toList();
 	}
 }

src/main/java/com/imyeyu/inject/annotation/PostConstruct.java

@@ -13,4 +13,11 @@ import java.lang.annotation.Target;
 @Target(ElementType.METHOD)
 @Retention(RetentionPolicy.RUNTIME)
 public @interface PostConstruct {
+
+	/**
+	 * 执行顺序，数值越小越先执行，默认为 0
+	 *
+	 * @return 执行顺序
+	 */
+	int value() default 0;
 }

src/main/java/com/imyeyu/inject/annotation/Qualifier.java

@@ -10,7 +10,7 @@ import java.lang.annotation.Target;
  *
  * @author 夜雨
  */
-@Target(ElementType.PARAMETER)
+@Target({ElementType.PARAMETER, ElementType.FIELD})
 @Retention(RetentionPolicy.RUNTIME)
 public @interface Qualifier {