feat: Refactor project structure for modularity and expandability

- Implemented the service and adapter layers instead of controllers to simplify the integration of new audio recognition and metadata fetching APIs.
- Unified code styling and practices throughout the project to ensure consistency.

src/api/recognition/auddApi.js

@@ -0,0 +1,34 @@
+import fs from 'fs';
+import axios from 'axios';
+import axiosRetry from '../../utils/retryAxios.js';
+import handleError from '../../errors/generalApiErrorHandler.js';
+
+export default async function auddAudioRecognition(filePath) {
+  const audioData = fs.readFileSync(filePath);
+  const base64Audio = Buffer.from(audioData).toString('base64');
+  const body = new URLSearchParams({
+    api_token: process.env.AUDD_API_TOKEN,
+    audio: base64Audio,
+    return: 'spotify',
+  });
+
+  const requestOptions = {
+    headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
+  };
+
+  return axios.post('https://api.audd.io/', new URLSearchParams(body), requestOptions)
+    .then((response) => {
+      const { data } = response;
+
+      if (!data) throw new Error('No data received from Audd API');
+      if (data.error) throw new Error(`Audd API Error: ${JSON.stringify(data.error)}`);
+
+      console.log('Recognition successful for:', filePath);
+      return data;
+    })
+    .catch((error) => {
+      console.error('Error recognizing audio');
+      const errorMessage = handleError(error, filePath);
+      throw new Error(errorMessage);
+    });
+}