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-config/src/error.rs

@@ -0,0 +1,143 @@
+use erp_core::error::AppError;
+
+/// Config module error types.
+#[derive(Debug, thiserror::Error)]
+pub enum ConfigError {
+    #[error("验证失败: {0}")]
+    Validation(String),
+
+    #[error("资源未找到: {0}")]
+    NotFound(String),
+
+    #[error("键已存在: {0}")]
+    DuplicateKey(String),
+
+    #[error("编号序列耗尽: {0}")]
+    NumberingExhausted(String),
+
+    #[error("版本冲突: 数据已被其他操作修改，请刷新后重试")]
+    VersionMismatch,
+}
+
+impl From<sea_orm::TransactionError<ConfigError>> for ConfigError {
+    fn from(err: sea_orm::TransactionError<ConfigError>) -> Self {
+        match err {
+            sea_orm::TransactionError::Connection(err) => ConfigError::Validation(err.to_string()),
+            sea_orm::TransactionError::Transaction(inner) => inner,
+        }
+    }
+}
+
+impl From<sea_orm::DbErr> for ConfigError {
+    fn from(err: sea_orm::DbErr) -> Self {
+        ConfigError::Validation(err.to_string())
+    }
+}
+
+impl From<ConfigError> for AppError {
+    fn from(err: ConfigError) -> Self {
+        match err {
+            ConfigError::Validation(s) => AppError::Validation(s),
+            ConfigError::NotFound(s) => AppError::NotFound(s),
+            ConfigError::DuplicateKey(s) => AppError::Conflict(s),
+            ConfigError::NumberingExhausted(s) => AppError::Internal(s),
+            ConfigError::VersionMismatch => AppError::VersionMismatch,
+        }
+    }
+}
+
+pub type ConfigResult<T> = Result<T, ConfigError>;
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use erp_core::error::AppError;
+
+    #[test]
+    fn config_error_validation_maps_to_app_validation() {
+        let app: AppError = ConfigError::Validation("字段不能为空".to_string()).into();
+        match app {
+            AppError::Validation(msg) => assert_eq!(msg, "字段不能为空"),
+            other => panic!("期望 Validation，实际得到 {:?}", other),
+        }
+    }
+
+    #[test]
+    fn config_error_not_found_maps_to_app_not_found() {
+        let app: AppError = ConfigError::NotFound("字典不存在".to_string()).into();
+        match app {
+            AppError::NotFound(msg) => assert_eq!(msg, "字典不存在"),
+            other => panic!("期望 NotFound，实际得到 {:?}", other),
+        }
+    }
+
+    #[test]
+    fn config_error_duplicate_key_maps_to_app_conflict() {
+        let app: AppError = ConfigError::DuplicateKey("编码已存在".to_string()).into();
+        match app {
+            AppError::Conflict(msg) => assert_eq!(msg, "编码已存在"),
+            other => panic!("期望 Conflict，实际得到 {:?}", other),
+        }
+    }
+
+    #[test]
+    fn config_error_numbering_exhausted_maps_to_app_internal() {
+        let app: AppError = ConfigError::NumberingExhausted("序列已耗尽".to_string()).into();
+        match app {
+            AppError::Internal(msg) => assert!(msg.contains("序列已耗尽")),
+            other => panic!("期望 Internal，实际得到 {:?}", other),
+        }
+    }
+
+    #[test]
+    fn config_error_version_mismatch_maps_to_app_version_mismatch() {
+        let app: AppError = ConfigError::VersionMismatch.into();
+        match app {
+            AppError::VersionMismatch => {}
+            other => panic!("期望 VersionMismatch，实际得到 {:?}", other),
+        }
+    }
+
+    #[test]
+    fn config_error_display_messages() {
+        // 验证各变体的 Display 输出包含中文描述
+        assert!(
+            ConfigError::Validation("test".into())
+                .to_string()
+                .contains("验证失败")
+        );
+        assert!(
+            ConfigError::NotFound("test".into())
+                .to_string()
+                .contains("资源未找到")
+        );
+        assert!(
+            ConfigError::DuplicateKey("test".into())
+                .to_string()
+                .contains("键已存在")
+        );
+        assert!(
+            ConfigError::NumberingExhausted("test".into())
+                .to_string()
+                .contains("编号序列耗尽")
+        );
+        assert!(
+            ConfigError::VersionMismatch
+                .to_string()
+                .contains("版本冲突")
+        );
+    }
+
+    #[test]
+    fn transaction_error_connection_maps_to_validation() {
+        // TransactionError::Connection 应该转换为 ConfigError::Validation
+        let config_err: ConfigError = sea_orm::TransactionError::Connection(sea_orm::DbErr::Conn(
+            sea_orm::RuntimeErr::Internal("连接失败".to_string()),
+        ))
+        .into();
+        match config_err {
+            ConfigError::Validation(msg) => assert!(msg.contains("连接失败")),
+            other => panic!("期望 Validation，实际得到 {:?}", other),
+        }
+    }
+}