feat: Refactor BedHardware to support both Serial and MQTT implementations

- Added MQTT support to BedHardware, allowing for connection to MQTT brokers.
- Created BedHardwareMQTT and BedHardwareSerial classes to handle respective connections.
- Introduced a unified BedHardwareConfig interface for configuration management.
- Implemented event forwarding from the underlying implementations to the BedHardware class.
- Added MQTT adapter for handling MQTT connections and message subscriptions.
- Updated package.json to include the mqtt library as a dependency.
- Created a singleton MQTTService for managing MQTT client instances.
- Enhanced error handling and logging throughout the BedHardware and MQTT classes.

services/mqttService.ts

@@ -0,0 +1,72 @@
+import MQTT, { MQTTConfig } from '../adapter/mqtt';
+
+// Default MQTT configuration for HiveMQ broker
+const defaultConfig: MQTTConfig = {
+  host: 'broker.hivemq.com',
+  port: 1883,
+  username: undefined,
+  password: undefined
+};
+
+export const BASE_TOPIC = '/Jtkcp2N/pressurebed/';
+
+// Singleton MQTT client instance
+let mqttInstance: MQTT | null = null;
+
+export class MQTTService {
+  private static instance: MQTT | null = null;
+
+  static async initialize(config?: Partial<MQTTConfig>): Promise<MQTT> {
+    if (!MQTTService.instance) {
+      const finalConfig = { ...defaultConfig, ...config };
+      MQTTService.instance = new MQTT();
+      await MQTTService.instance.initialize(finalConfig);
+    }
+    return MQTTService.instance;
+  }
+
+  static getInstance(): MQTT | null {
+    return MQTTService.instance;
+  }
+
+  static async disconnect(): Promise<void> {
+    if (MQTTService.instance) {
+      await MQTTService.instance.disconnect();
+      MQTTService.instance = null;
+    }
+  }
+}
+
+// Factory function to get or create MQTT client
+export async function getMQTTClient(config?: Partial<MQTTConfig>): Promise<MQTT> {
+  if (!mqttInstance) {
+    mqttInstance = new MQTT();
+    const finalConfig = { ...defaultConfig, ...config };
+    await mqttInstance.initialize(finalConfig);
+  }
+  return mqttInstance;
+}
+
+// Export the singleton instance getter
+export function getMQTTInstance(): MQTT | null {
+  return mqttInstance;
+}
+
+// Cleanup function
+export async function disconnectMQTT(): Promise<void> {
+  if (mqttInstance) {
+    await mqttInstance.disconnect();
+    mqttInstance = null;
+  }
+}
+
+// Export default configured client (lazy initialization)
+const mqttService = {
+  async getClient(config?: Partial<MQTTConfig>): Promise<MQTT> {
+    return getMQTTClient(config);
+  },
+  getInstance: getMQTTInstance,
+  disconnect: disconnectMQTT
+};
+
+export default mqttService;