Add chemistry/fouling telemetry to dashboard

src/reactor_sim/dashboard.py

@@ -736,9 +736,11 @@ class ReactorDashboard:
     def _heat_exchanger_lines(self, state: PlantState) -> list[tuple[str, str]]:
         delta_t = getattr(state, "primary_to_secondary_delta_t", 0.0)
         eff = getattr(state, "heat_exchanger_efficiency", 0.0)
+        hx_fouling = getattr(state, "hx_fouling", 0.0)
         return [
             ("ΔT (pri-sec)", f"{delta_t:6.1f} K"),
             ("HX Eff", f"{eff*100:6.1f}%"),
+            ("Chem/Foul", f"O2 {getattr(state, 'dissolved_oxygen_ppm', 0.0):5.1f} ppm Na {getattr(state, 'sodium_ppm', 0.0):5.1f} ppm Foul {hx_fouling*100:5.1f}%"),
         ]
 
     def _protection_lines(self, state: PlantState) -> list[tuple[str, str]]: