refactor: simplify simulation validation logic and update non-default duration requirements

src/calculation_target_reliability/router.py

@@ -92,13 +92,7 @@ async def get_target_reliability(
     #     oh_duration=duration
     # )
     
-    if duration != 17520:
+    if simulation_id:
-        if not simulation_id:
-            raise HTTPException(
-                    status_code=status.HTTP_400_BAD_REQUEST,
-                    detail="Simulation ID is required for non-default duration. Please run simulation first.",
-            )
-        else:
         try:
             temporal_client = await Client.connect(TEMPORAL_URL)
             handle = temporal_client.get_workflow_handle(f"simulation-{simulation_id}")
@@ -124,6 +118,11 @@ async def get_target_reliability(
                 detail=f"Simulation not found or error checking status: {str(e)}",
             )
     else:
+        if duration != 17520 or oh_duration != 1200:
+             raise HTTPException(
+                    status_code=status.HTTP_400_BAD_REQUEST,
+                    detail="Simulation ID is required for non-default duration or OH duration. Please run simulation first.",
+            )
         simulation_id = TR_RBD_ID