add UML diagram for system architecture and clean up MQTT client initialization

docs/Infrastructure/uml.md

@@ -0,0 +1,51 @@
+```mermaid
+classDiagram
+    class CKobuki {
+        +enableCommands(bool commands)
+        +loop(void *user_data, TKobukiData &Kobuki_data)
+        +startCommunication(char *portname, bool CommandsEnabled, void *userDataL)
+        +measure()
+        +setLed(int led1, int led2)
+        +setTranslationSpeed(int mmpersec)
+        +setRotationSpeed(double radpersec)
+        +setArcSpeed(int mmpersec, int radius)
+        +setSound(int noteinHz, int duration)
+        +setPower(int value)
+        +goStraight(long double distance)
+        +forward(int speedvalue)
+        +doRotation(long double th)
+    }
+
+    class FlaskApp {
+        +on_message(client, message)
+        +get_db()
+        +close_db(error)
+        +index()
+        +control()
+        +move()
+    }
+
+    class MQTTClient {
+        +connect()
+        +subscribe(topic)
+        +getLastMessage()
+        +isConnected()
+    }
+
+    FlaskApp --> MQTTClient : uses
+    FlaskApp --> CKobuki : controls
+
+    class RPI {
+        +KobukiCommunication()
+        +ESP32Communication()
+        +Camera()
+    }
+
+    class ESP32 {
+        +TVOC()
+        +DHT11()
+    }
+
+    RPI --> MQTTClient : communicates
+    MQTTClient --> CKobuki : communicates
+    RPI --> ESP32 : communicates