Persist config through backend controller

simulator/esp32_sim.py

@@ -35,11 +35,19 @@ class ESP32Simulator:
         self.soc = 82.0
         self.last_update = time.time()
 
+    def config_path(self):
+        return Path(__file__).parent / "config.json"
+
     def load_config(self):
-        config_path = Path(__file__).parent / "config.json"
-        with config_path.open() as f:
+        with self.config_path().open() as f:
             return json.load(f)
 
+    def save_config(self, config):
+        with self.config_path().open("w") as f:
+            json.dump(config, f, indent=2)
+
+        return self.load_config()
+
     def update_battery(self):
         now = time.time()
         elapsed_hours = (now - self.last_update) / 3600