Fix dashboard simulation speed with time multiplier

- Add time multiplier control (1× to 100× speed)
- Calculate steps based on real elapsed time
- Add 50ms delay to prevent UI thrashing
- Display current speed in Sim Time metric

src/py_dvt_ate/app/dashboard/app.py

@@ -4,6 +4,7 @@ This module provides an interactive dashboard for visualising the physics
 engine directly, demonstrating thermal-electrical coupling in real-time.
 """
 
+import time
 from collections import deque
 from dataclasses import dataclass, field
 
@@ -15,6 +16,11 @@ from py_dvt_ate.simulation.physics.engine import PhysicsEngine
 # History buffer size for charts
 HISTORY_SIZE = 500
 
+# Simulation speed settings
+DEFAULT_TIME_MULTIPLIER = 10.0  # 10x faster than real-time
+STEPS_PER_UPDATE = 100  # Steps per UI refresh
+UPDATE_INTERVAL_MS = 100  # Target UI refresh rate
+
 
 @dataclass
 class SimulationHistory:
@@ -44,12 +50,29 @@ def init_session_state() -> None:
         st.session_state.history = SimulationHistory()
     if "running" not in st.session_state:
         st.session_state.running = False
+    if "time_multiplier" not in st.session_state:
+        st.session_state.time_multiplier = DEFAULT_TIME_MULTIPLIER
+    if "last_update" not in st.session_state:
+        st.session_state.last_update = time.time()
 
 
-def step_simulation(steps: int = 10) -> None:
+def step_simulation() -> None:
-    """Advance the simulation by the given number of steps."""
+    """Advance the simulation based on elapsed real time and multiplier."""
     engine: PhysicsEngine = st.session_state.engine
     history: SimulationHistory = st.session_state.history
+    multiplier: float = st.session_state.time_multiplier
+
+    # Calculate how much simulation time to advance
+    current_time = time.time()
+    elapsed_real = current_time - st.session_state.last_update
+    st.session_state.last_update = current_time
+
+    # Simulation time to advance (capped to prevent huge jumps)
+    sim_time_to_advance = min(elapsed_real * multiplier, 2.0)
+
+    # Calculate number of steps needed
+    steps = int(sim_time_to_advance / engine.dt)
+    steps = max(1, min(steps, 1000))  # Clamp between 1 and 1000 steps
 
     for _ in range(steps):
         engine.step()
@@ -177,7 +200,11 @@ def display_current_state() -> None:
     with col7:
         st.metric("Power Diss.", f"{electrical.power_dissipation * 1000:.2f} mW")
     with col8:
-        st.metric("Sim Time", f"{engine.simulation_time:.2f} s")
+        st.metric(
+            "Sim Time",
+            f"{engine.simulation_time:.1f} s",
+            delta=f"{st.session_state.time_multiplier:.0f}× speed",
+        )
 
 
 def display_controls() -> None:
@@ -203,10 +230,25 @@ def display_controls() -> None:
         st.session_state.engine = PhysicsEngine(update_rate_hz=100.0)
         st.session_state.history = SimulationHistory()
         st.session_state.running = False
+        st.session_state.last_update = time.time()
         st.rerun()
 
     st.sidebar.divider()
 
+    # Time multiplier
+    st.sidebar.subheader("Simulation Speed")
+    time_mult = st.sidebar.select_slider(
+        "Time Multiplier",
+        options=[1, 2, 5, 10, 20, 50, 100],
+        value=int(st.session_state.time_multiplier),
+        format_func=lambda x: f"{x}×",
+        key="time_mult_slider",
+    )
+    st.session_state.time_multiplier = float(time_mult)
+    st.sidebar.caption(f"1 real second = {time_mult} simulation seconds")
+
+    st.sidebar.divider()
+
     # Temperature setpoint
     st.sidebar.subheader("Thermal Chamber")
     temp_setpoint = st.sidebar.slider(
@@ -290,7 +332,8 @@ def main() -> None:
 
     # Auto-refresh when running
     if st.session_state.running:
-        step_simulation(steps=10)
+        step_simulation()
+        time.sleep(0.05)  # Small delay to prevent UI thrashing
         st.rerun()