Add optional rich-based alternate dashboard

src/reactor_sim/simulation.py

@@ -95,6 +95,7 @@ def main() -> None:
     log_file = os.getenv("FISSION_LOG_FILE")
     configure_logging(log_level, log_file)
     realtime = os.getenv("FISSION_REALTIME", "0") == "1"
+    alternate_dashboard = os.getenv("ALTERNATE_DASHBOARD", "0") == "1"
     duration_env = os.getenv("FISSION_SIM_DURATION")
     if duration_env:
         duration = None if duration_env.lower() in {"none", "infinite"} else float(duration_env)
@@ -117,16 +118,31 @@ def main() -> None:
     if load_path:
         sim.start_state = reactor.load_state(load_path)
     if dashboard_mode:
-        from .dashboard import ReactorDashboard
+        if alternate_dashboard:
+            try:
+                from .rich_dashboard import RichDashboard
+            except ImportError as exc:  # pragma: no cover - optional dependency
+                LOGGER.error("Rich dashboard requested but 'rich' is not installed: %s", exc)
+                return
+            dashboard = RichDashboard(
+                reactor,
+                start_state=sim.start_state,
+                timestep=sim.timestep,
+                save_path=save_path,
+            )
+            dashboard.run()
+            return
+        else:
+            from .dashboard import ReactorDashboard
 
-        dashboard = ReactorDashboard(
-            reactor,
-            start_state=sim.start_state,
-            timestep=sim.timestep,
-            save_path=save_path,
-        )
-        dashboard.run()
-        return
+            dashboard = ReactorDashboard(
+                reactor,
+                start_state=sim.start_state,
+                timestep=sim.timestep,
+                save_path=save_path,
+            )
+            dashboard.run()
+            return
     try:
         if realtime:
             LOGGER.info("Running in real-time mode (Ctrl+C to stop)...")