fix(07-12): deleteModifierByIndex 委托 deleteModifier（WR-05）

- 按索引取出修饰器后委托 deleteModifier，删除簿记收敛为一份实现
- 返回被删修饰器；索引越界或为负返回 null 且不删除任何修饰器
- 回归覆盖：迭代器产出、索引解析、final 重算、重新挂载、存盘开关清理、越界

packages-user/data-base/src/hero/attribute.test.ts

@@ -203,6 +203,60 @@ describe('HeroAttribute modifier management', () => {
         expect(attribute.deleteModifierByIndex('hp', 0)).toBeNull();
     });
 
+    // 验证按索引删除后修饰器不再被迭代、索引解析为 -1 且最终属性按剩余修饰器重算
+    it('removes a modifier by index from the iterator and the final attribute', () => {
+        const attribute = createAttribute();
+        const first = new TestModifier(5, 10);
+        const second = new TestModifier(2, 0);
+        attribute.addModifier('hp', first);
+        attribute.addModifier('hp', second);
+        expect(attribute.getFinalAttribute('hp')).toBe(107);
+
+        expect(attribute.deleteModifierByIndex('hp', 0)).toBe(first);
+        expect([...attribute.iterateModifiers()]).toEqual([['hp', second]]);
+        expect(attribute.getModifierIndex(first)).toBe(-1);
+        expect(attribute.getFinalAttribute('hp')).toBe(102);
+    });
+
+    // 验证被按索引删除的修饰器已解除归属，可以重新挂载且不再被码 108 拒绝
+    it('allows an index-deleted modifier to be attached again', () => {
+        const attribute = createAttribute();
+        const first = new TestModifier(5);
+        attribute.addModifier('hp', first);
+
+        expect(attribute.deleteModifierByIndex('hp', 0)).toBe(first);
+
+        const result = logger.catch(() => attribute.addModifier('hp', first));
+        expect(result.info.map(info => info.code)).not.toContain(108);
+        expect(attribute.getModifierIndex(first)).toBe(0);
+        expect(attribute.getFinalAttribute('hp')).toBe(105);
+    });
+
+    // 验证索引越界或为负时返回 null 且不删除任何修饰器
+    it('keeps every modifier when the index is out of range', () => {
+        const attribute = createAttribute();
+        const first = new TestModifier(5, 10);
+        const second = new TestModifier(2, 0);
+        attribute.addModifier('hp', first);
+        attribute.addModifier('hp', second);
+
+        expect(attribute.deleteModifierByIndex('hp', -1)).toBeNull();
+        expect(attribute.deleteModifierByIndex('hp', 2)).toBeNull();
+        expect([...attribute.getModifiers('hp')]).toEqual([first, second]);
+        expect(attribute.getFinalAttribute('hp')).toBe(107);
+    });
+
+    // 验证按索引删除不存档修饰器时其存盘开关记录被一并清理
+    it('clears the save flag of an index-deleted modifier', () => {
+        const attribute = createAttribute();
+        const unsaved = new TestModifier(3);
+        attribute.addModifier('hp', unsaved, false);
+        expect(attribute.getModifierSaveEnabled(unsaved)).toBe(false);
+
+        expect(attribute.deleteModifierByIndex('hp', 0)).toBe(unsaved);
+        expect(attribute.getModifierSaveEnabled(unsaved)).toBe(true);
+    });
+
     // 验证存盘开关可分别设置与查询
     it('tracks the per-modifier save flag', () => {
         const attribute = createAttribute();

packages-user/data-base/src/hero/attribute.ts

@@ -233,9 +233,12 @@ export class HeroAttribute<THero> implements IHeroAttribute<THero> {
     ): IHeroModifier<THero[K]> | null {
         const arr = this.modifier.get(name);
         if (!arr) return null;
-        const modifier = arr.splice(index, 1);
-        if (modifier.length === 0) return null;
-        else return modifier[0] as IHeroModifier<THero[K]>;
+        const modifier = arr[index] as IHeroModifier<THero[K]> | undefined;
+        // 越界与负索引一律不删除任何修饰器，避免旧 splice 语义下误删末尾元素
+        if (!modifier) return null;
+        // 删除簿记统一由 deleteModifier 承担，故需先取出修饰器再委托以保留返回值
+        this.deleteModifier(name, modifier);
+        return modifier;
     }
 
     markDirty(name: keyof THero): void {

packages-user/data-base/src/hero/types.ts

@@ -219,7 +219,8 @@ export interface IHeroAttribute<THero>
     ): void;
 
     /**
-     * 根据修饰器索引删除指定修饰器
+     * 根据修饰器索引删除指定修饰器。删除簿记与 `deleteModifier` 共用同一份实现，
+     * 修饰器会被解绑且不再属于本属性；索引越界或为负时返回 `null`，且不删除任何修饰器
      * @param name 属性名称
      * @param index 修饰器索引
      * @returns 被删除的修饰器