feat: initialize Nuanji (Warm Notes) project

- Base platform from base.git (ERP base: auth, core, config, message, workflow, plugin)
- Created erp-diary module skeleton (lib.rs, dto.rs, error.rs, event.rs, state.rs)
- Integrated erp-diary into workspace and erp-server
- Added DiaryModule registration in main.rs
- Added DiaryState FromRef in state.rs
- Diary routes mounted (empty routes, ready for implementation)
- Product design spec v1.2 preserved in docs/
- Implementation plan preserved in plans/

Cargo check: OK
Cargo test: OK (78+ base tests passing)

crates/erp-diary/src/dto.rs

@@ -0,0 +1,125 @@
+// erp-diary 数据传输对象 (DTO)
+
+use serde::{Deserialize, Serialize};
+use utoipa::ToSchema;
+
+/// 日记心情枚举
+#[derive(Debug, Clone, Serialize, Deserialize, ToSchema)]
+#[serde(rename_all = "lowercase")]
+pub enum Mood {
+    Happy,
+    Calm,
+    Sad,
+    Angry,
+    Thinking,
+}
+
+/// 天气枚举
+#[derive(Debug, Clone, Serialize, Deserialize, ToSchema)]
+#[serde(rename_all = "lowercase")]
+pub enum Weather {
+    Sunny,
+    Cloudy,
+    Rainy,
+    Snowy,
+    Windy,
+}
+
+/// 创建日记请求
+#[derive(Debug, Deserialize, ToSchema)]
+pub struct CreateJournalReq {
+    pub title: String,
+    pub date: chrono::NaiveDate,
+    pub mood: Mood,
+    pub weather: Weather,
+    pub tags: Vec<String>,
+    pub is_private: bool,
+    pub class_id: Option<uuid::Uuid>,
+    pub assigned_topic_id: Option<uuid::Uuid>,
+}
+
+/// 更新日记请求
+#[derive(Debug, Deserialize, ToSchema)]
+pub struct UpdateJournalReq {
+    pub title: Option<String>,
+    pub mood: Option<Mood>,
+    pub weather: Option<Weather>,
+    pub tags: Option<Vec<String>>,
+    pub is_private: Option<bool>,
+    pub shared_to_class: Option<bool>,
+    pub version: i32,
+}
+
+/// 日记响应
+#[derive(Debug, Serialize, ToSchema)]
+pub struct JournalResp {
+    pub id: uuid::Uuid,
+    pub author_id: uuid::Uuid,
+    pub class_id: Option<uuid::Uuid>,
+    pub title: String,
+    pub date: chrono::NaiveDate,
+    pub mood: Mood,
+    pub weather: Weather,
+    pub tags: Vec<String>,
+    pub is_private: bool,
+    pub shared_to_class: bool,
+    pub version: i32,
+    pub created_at: chrono::DateTime<chrono::Utc>,
+    pub updated_at: chrono::DateTime<chrono::Utc>,
+}
+
+/// 创建班级请求
+#[derive(Debug, Deserialize, ToSchema)]
+pub struct CreateClassReq {
+    pub name: String,
+    pub school_name: Option<String>,
+}
+
+/// 加入班级请求
+#[derive(Debug, Deserialize, ToSchema)]
+pub struct JoinClassReq {
+    pub class_code: String,
+}
+
+/// 班级响应
+#[derive(Debug, Serialize, ToSchema)]
+pub struct ClassResp {
+    pub id: uuid::Uuid,
+    pub name: String,
+    pub school_name: Option<String>,
+    pub teacher_id: uuid::Uuid,
+    pub class_code: String,
+    pub member_count: i32,
+    pub is_active: bool,
+}
+
+/// 同步请求
+#[derive(Debug, Deserialize, ToSchema)]
+pub struct SyncReq {
+    pub last_sync_time: Option<chrono::DateTime<chrono::Utc>>,
+    pub changes: Vec<SyncChange>,
+}
+
+/// 同步变更条目
+#[derive(Debug, Deserialize, ToSchema)]
+pub enum SyncChange {
+    CreateJournal { data: serde_json::Value },
+    UpdateJournal { id: uuid::Uuid, version: i32, data: serde_json::Value },
+    DeleteJournal { id: uuid::Uuid, version: i32 },
+}
+
+/// 同步响应
+#[derive(Debug, Serialize, ToSchema)]
+pub struct SyncResp {
+    pub server_changes: Vec<serde_json::Value>,
+    pub conflicts: Vec<ConflictInfo>,
+    pub sync_time: chrono::DateTime<chrono::Utc>,
+}
+
+/// 冲突信息
+#[derive(Debug, Serialize, ToSchema)]
+pub struct ConflictInfo {
+    pub journal_id: uuid::Uuid,
+    pub local_version: i32,
+    pub server_version: i32,
+}