fix: standardize role case handling in permission logic

Co-authored-by: aider (openai/DeepSeek-V3.2-Thinking) <aider@aider.chat>

inventory-web/src/stores/user.ts

@@ -35,7 +35,8 @@ export const useUserStore = defineStore('user', () => {
 
         // 处理用户信息 (确保后端返回结构中有 user 字段)
         if (data.user) {
-            role.value = data.user.role || 'user' // 默认给个 user 角色防止空
+            const rawRole = data.user.role || 'user'
+            role.value = rawRole.toUpperCase() // 角色统一转换为大写
             username.value = data.user.username || '用户'
 
             // 持久化存储用户信息