Implement sample audio retrieval and update playback functionality

- Added a new API endpoint to serve profile sample audio files.
- Introduced a method in the apiClient to generate sample audio URLs.
- Refactored the SampleList component to utilize the new API for audio playback, enhancing the user experience.
- Cleaned up unused imports and optimized the handlePlay function for better performance.

app/src/lib/api/client.ts

@@ -146,6 +146,10 @@ class ApiClient {
     return `${this.getBaseUrl()}/audio/${audioId}`;
   }
 
+  getSampleUrl(sampleId: string): string {
+    return `${this.getBaseUrl()}/samples/${sampleId}`;
+  }
+
   // Transcription
   async transcribeAudio(file: File, language?: 'en' | 'zh'): Promise<TranscriptionResponse> {
     const formData = new FormData();