feat(auth): add SeaORM entities and DTOs for auth module

- 11 entity files mapping to all auth migration tables
- DTOs with validation: LoginReq, CreateUserReq, CreateRoleReq, etc.
- Response DTOs: UserResp, RoleResp, PermissionResp, OrganizationResp, etc.
- Added workspace dependencies: jsonwebtoken, argon2, validator, thiserror, utoipa

crates/erp-auth/src/lib.rs

@@ -1 +1,2 @@
-// erp-auth: 身份与权限模块 (Phase 2)
+pub mod dto;
+pub mod entity;