fix(07-04): #06-05-2 prefer the first empty named slot

- getCouldEquipSlot tests empty === -1 so the first empty named slot wins instead of always replacing the first match
- un-skip the named-slot empty-preference case; canEquipTo string branch untouched

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

@@ -286,8 +286,8 @@ describe('HeroEquipment equip and unequip', () => {
         expect(equips[1]).toBeNull();
     });
 
-    // 疑似 bug：字符串槽位空槽判断条件写反导致总是替换首个匹配槽位，详见 06-TEST-FINDINGS.md #06-05-2
-    it.skip('uses the first empty named slot instead of replacing an occupant', () => {
+    // 验证字符串槽位优先占用首个空槽而非替换占用者（#06-05-2）
+    it('uses the first empty named slot instead of replacing an occupant', () => {
         const env = createEnv();
         registerItem(env, createItem(10, 'sword', ['weapon'], [['atk', 5]]));
         registerItem(env, createItem(11, 'axe', ['weapon'], [['atk', 12]]));

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

@@ -138,7 +138,7 @@ export class HeroEquipment<THero> implements IHeroEquipment<THero> {
         this.slots.forEach((name, index) => {
             if (name !== slot) return;
             if (first === -1) first = index;
-            if (empty !== -1 && !this.equips.has(index)) {
+            if (empty === -1 && !this.equips.has(index)) {
                 empty = index;
             }
         });