feat(permission): 完成Phase 2权限核心模块后端

新增:
- PermissionRepository/Service/Controller
- DepartmentRepository/Service/Controller
- PermissionCheckService 权限判断服务
- SysPermission、SysDepartment 实体类

Phase 2后端基础完成约60%

src/main/java/com/mosquito/project/permission/PermissionRepository.java

@@ -0,0 +1,29 @@
+package com.mosquito.project.permission;
+
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.stereotype.Repository;
+
+import java.util.List;
+import java.util.Optional;
+
+/**
+ * 权限Repository
+ */
+@Repository
+public interface PermissionRepository extends JpaRepository<SysPermission, Long> {
+
+    /**
+     * 根据权限代码查询
+     */
+    Optional<SysPermission> findByPermissionCode(String permissionCode);
+
+    /**
+     * 根据模块代码查询
+     */
+    List<SysPermission> findByModuleCode(String moduleCode);
+
+    /**
+     * 检查权限代码是否存在
+     */
+    boolean existsByPermissionCode(String permissionCode);
+}