refactor(diary): Phase 3 质量提升 — 201 状态码 + OpenAPI 文档 + DiaryEvent 类型安全

前端:
- fix(app): Isar native 文件直接导入 isar_database_native.dart，消除 5 个条件导出类型错误
- chore(app): build_runner 重新生成 .g.dart 文件 (102 outputs)
- fix(app): 移除 secure_token_store_factory 未使用的 kIsWeb import

后端:
- refactor(diary): 所有创建端点 POST 返回 201 Created (9 handler, 11 端点)
- feat(diary): DiaryApiDoc OpenApi derive — 42 路径 + 32 Schema 汇总到 Swagger
- feat(diary): DiaryEvent 枚举添加 event_type/payload/to_domain_event 方法 + 4 测试

测试: 84/84 erp-diary 通过, 509/509 全仓库通过, Flutter analyze 0 error

crates/erp-diary/src/handler/class_handler.rs

@@ -1,6 +1,7 @@
 // 班级 API 处理器 — 创建班级、加入班级、查询班级
 
 use axum::extract::{Extension, FromRef, Path, State};
+use axum::http::StatusCode;
 use axum::response::Json;
 use uuid::Uuid;
 use validator::Validate;
@@ -18,7 +19,7 @@ use crate::state::DiaryState;
     path = "/api/v1/diary/classes",
     request_body = CreateClassReq,
     responses(
-        (status = 200, description = "创建成功", body = ApiResponse<ClassResp>),
+        (status = 201, description = "创建成功", body = ApiResponse<ClassResp>),
         (status = 400, description = "验证失败"),
         (status = 401, description = "未授权"),
         (status = 403, description = "权限不足"),
@@ -33,7 +34,7 @@ pub async fn create_class<S>(
     State(state): State<DiaryState>,
     Extension(ctx): Extension<TenantContext>,
     Json(req): Json<CreateClassReq>,
-) -> Result<Json<ApiResponse<ClassResp>>, AppError>
+) -> Result<(StatusCode, Json<ApiResponse<ClassResp>>), AppError>
 where
     DiaryState: FromRef<S>,
     S: Clone + Send + Sync + 'static,
@@ -55,7 +56,7 @@ where
     )
     .await?;
 
-    Ok(Json(ApiResponse::ok(resp)))
+    Ok((StatusCode::CREATED, Json(ApiResponse::ok(resp))))
 }
 
 #[utoipa::path(
@@ -63,7 +64,7 @@ where
     path = "/api/v1/diary/classes/join",
     request_body = JoinClassReq,
     responses(
-        (status = 200, description = "加入成功", body = ApiResponse<ClassResp>),
+        (status = 201, description = "加入成功", body = ApiResponse<ClassResp>),
         (status = 400, description = "班级码无效或已过期"),
         (status = 401, description = "未授权"),
         (status = 403, description = "权限不足"),
@@ -78,7 +79,7 @@ pub async fn join_class<S>(
     State(state): State<DiaryState>,
     Extension(ctx): Extension<TenantContext>,
     Json(req): Json<JoinClassReq>,
-) -> Result<Json<ApiResponse<ClassResp>>, AppError>
+) -> Result<(StatusCode, Json<ApiResponse<ClassResp>>), AppError>
 where
     DiaryState: FromRef<S>,
     S: Clone + Send + Sync + 'static,
@@ -101,7 +102,7 @@ where
     )
     .await?;
 
-    Ok(Json(ApiResponse::ok(resp)))
+    Ok((StatusCode::CREATED, Json(ApiResponse::ok(resp))))
 }
 
 #[utoipa::path(