fix(simulation): export ACTIVE valves correctly for EPANET 2

The legacy online simulation path still exported internal ACTIVE states as STATUS keywords, which EPANET 2 rejects. Preserve numeric settings and EPANET 3 output while passing the format through both exporters. Surface the original engine error inside the model transaction so failed runs roll back before result storage.

Regression guard: six failures reproduced on the deployed baseline, including native input validation. All 34 focused export, service and endpoint checks pass after the fix; the real project also returns native node and link results.

app/services/simulation.py

@@ -490,6 +490,23 @@ def run_simulation(
                     set_status(name_c, cs)
         # 运行并返回结果
         result_data = json.loads(run_project(name_c))
+        if result_data.get("simulation_result") == "failed":
+            report = result_data.get("report") or ""
+            logging.error("EPANET failed for project %s:\n%s", name_c, report)
+            lines = report.splitlines()
+            error_index = next(
+                (i for i, line in enumerate(lines) if line.strip().startswith("Error ")),
+                None,
+            )
+            detail = (
+                " ".join(line.strip() for line in lines[error_index:error_index + 2])[:600]
+                if error_index is not None
+                else "引擎未返回错误详情，请查看服务日志"
+            )
+            raise RuntimeError(f"EPANET 计算失败：{detail}")
+        output_data = result_data.get("output")
+        if not isinstance(output_data, dict):
+            raise RuntimeError("run_project did not return JSON output content")
     refresh_materialized_views_after_commit(name_c)
     time_cost_end = time.perf_counter()
     print(
@@ -498,9 +515,6 @@ def run_simulation(
             time_cost_end - time_cost_start,
         )
     )
-    output_data = result_data.get("output")
-    if not isinstance(output_data, dict):
-        raise RuntimeError("run_project did not return JSON output content")
     node_result = output_data.get("node_results")
     link_result = output_data.get("link_results")
     if node_result is None or link_result is None: