test(ai): erp-ai 从零增至 34 个单元测试 — 覆盖 DTO/error/prompt/sanitization

- dto.rs: 8 个测试（AnalysisType 映射、serde round-trip、SSE 事件、默认值）
- error.rs: 10 个测试（AiError 全部 10 个变体 → AppError 映射）
- prompt: 8 个测试（变量替换、嵌套对象、数组迭代、条件、严格模式缺失变量）
- sanitization: 8 个测试（4 种 DTO 脱敏通过、PII 字段检测、空数据边界）

crates/erp-ai/src/error.rs

@@ -57,3 +57,108 @@ impl From<sea_orm::DbErr> for AiError {
 }
 
 pub type AiResult<T> = Result<T, AiError>;
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn validation_maps_to_app_error_validation() {
+        let err = AiError::Validation("字段缺失".to_string());
+        let app: AppError = err.into();
+        match app {
+            AppError::Validation(msg) => assert!(msg.contains("字段缺失")),
+            other => panic!("期望 AppError::Validation，得到 {:?}", other),
+        }
+    }
+
+    #[test]
+    fn analysis_not_found_maps_to_not_found() {
+        let err = AiError::AnalysisNotFound("abc-123".to_string());
+        let app: AppError = err.into();
+        match app {
+            AppError::NotFound(msg) => assert!(msg.contains("分析结果")),
+            other => panic!("期望 AppError::NotFound，得到 {:?}", other),
+        }
+    }
+
+    #[test]
+    fn prompt_not_found_maps_to_not_found() {
+        let err = AiError::PromptNotFound("lab_report_interpretation".to_string());
+        let app: AppError = err.into();
+        match app {
+            AppError::NotFound(msg) => assert!(msg.contains("Prompt 模板")),
+            other => panic!("期望 AppError::NotFound，得到 {:?}", other),
+        }
+    }
+
+    #[test]
+    fn provider_unavailable_maps_to_internal() {
+        let err = AiError::ProviderUnavailable("Claude".to_string());
+        let app: AppError = err.into();
+        match app {
+            AppError::Internal(msg) => assert!(msg.contains("Claude")),
+            other => panic!("期望 AppError::Internal，得到 {:?}", other),
+        }
+    }
+
+    #[test]
+    fn provider_error_maps_to_internal() {
+        let err = AiError::ProviderError("超时".to_string());
+        let app: AppError = err.into();
+        match app {
+            AppError::Internal(msg) => assert!(msg.contains("超时")),
+            other => panic!("期望 AppError::Internal，得到 {:?}", other),
+        }
+    }
+
+    #[test]
+    fn sanitization_error_maps_to_internal() {
+        let err = AiError::SanitizationError("PII 泄漏".to_string());
+        let app: AppError = err.into();
+        match app {
+            AppError::Internal(msg) => assert!(msg.contains("PII 泄漏")),
+            other => panic!("期望 AppError::Internal，得到 {:?}", other),
+        }
+    }
+
+    #[test]
+    fn template_error_maps_to_internal() {
+        let err = AiError::TemplateError("语法错误".to_string());
+        let app: AppError = err.into();
+        match app {
+            AppError::Internal(msg) => assert!(msg.contains("语法错误")),
+            other => panic!("期望 AppError::Internal，得到 {:?}", other),
+        }
+    }
+
+    #[test]
+    fn rate_limit_maps_to_too_many_requests() {
+        let err = AiError::RateLimitExceeded;
+        let app: AppError = err.into();
+        match app {
+            AppError::TooManyRequests => {},
+            other => panic!("期望 AppError::TooManyRequests，得到 {:?}", other),
+        }
+    }
+
+    #[test]
+    fn version_mismatch_maps_directly() {
+        let err = AiError::VersionMismatch;
+        let app: AppError = err.into();
+        match app {
+            AppError::VersionMismatch => {},
+            other => panic!("期望 AppError::VersionMismatch，得到 {:?}", other),
+        }
+    }
+
+    #[test]
+    fn db_error_maps_to_internal() {
+        let err = AiError::DbError("连接失败".to_string());
+        let app: AppError = err.into();
+        match app {
+            AppError::Internal(msg) => assert!(msg.contains("连接失败")),
+            other => panic!("期望 AppError::Internal，得到 {:?}", other),
+        }
+    }
+}