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/core/base.py

@@ -1,7 +1,7 @@
 from __future__ import annotations
 
 from abc import ABC, abstractmethod
-from collections.abc import Mapping
+from collections.abc import Callable, Mapping
 from typing import TYPE_CHECKING, Any, ClassVar
 
 from app.simulation.core.catalog import ComponentDisplaySpec
@@ -28,6 +28,13 @@ class Component(ABC):
     # they override either stream hook, the closure planner retains the legacy
     # full-network thermofluid fixed point.
     PRESSURE_FLOW_DEPENDS_ON_STREAM: ClassVar[bool | None] = None
+    # Exact residual suffixes whose declared variables are summed, in order,
+    # to form a ``sumToZero`` flow equation.  The causal solver deliberately
+    # reads this capability from the concrete class ``__dict__``: subclasses
+    # must repeat the promise after changing any equation semantics.
+    PRESSURE_FLOW_EXACT_SUM_TO_ZERO_EQUATION_SUFFIXES: ClassVar[
+        frozenset[str]
+    ] = frozenset()
     PORTS: ClassVar[tuple[PortDefinition, ...]] = ()
     PARAMETERS: ClassVar[tuple[ParameterDefinition, ...]] = ()
     RESULT_VARIABLES: ClassVar[tuple[ResultVariableDefinition, ...]] = ()
@@ -245,6 +252,18 @@ class Component(ABC):
             for equation in self.pressure_flow_equation_residuals()
         )
 
+    def pressure_flow_equation_value_readers(
+        self,
+    ) -> Mapping[str, Callable[[], float]]:
+        """Return explicitly separable scalar residual readers.
+
+        The solver consumes this optional capability only when the concrete
+        component class declares the method itself.  Subclasses therefore
+        cannot accidentally inherit an equation-purity promise.
+        """
+
+        return {}
+
     def update_stream_outflows(self, connected_h: Mapping[str, float]) -> None:
         """Update connector outflow properties from current flow directions."""