整合求解器活动监控与步长回归证据

同步远端 PNL0003 诊断和大采样网格能力，语义合并活动感知的 60 秒真停滞判定与旧后端 15 分钟兼容兜底。

纳管热路径优化、15 单元运行证据、浏览器与 API 报告，并补充北京时间更新日志和遗留问题。

app/simulation/components/experimental/flow/orifice.py

@@ -17,6 +17,9 @@ class Orifice(AlgebraicComponent):
     MODEL_TYPE = "orifice"
     MODEL_VERSION = "1.0.0"
     PRESSURE_FLOW_DEPENDS_ON_STREAM = False
+    PRESSURE_FLOW_EXACT_SUM_TO_ZERO_EQUATION_SUFFIXES = frozenset(
+        ("mass_flow_balance",)
+    )
     PORTS = (
         PortDefinition.pneumatic("port_a", nominal_role="inlet"),
         PortDefinition.pneumatic("port_b", nominal_role="outlet"),
@@ -116,4 +119,3 @@ class Orifice(AlgebraicComponent):
     def update_stream_outflows(self, connected_h: Mapping[str, float]) -> None:
         self.port_a.h_outflow = connected_h["port_b"]
         self.port_b.h_outflow = connected_h["port_a"]
-