feat: add S3 storage support and update configuration

- Enhanced .env.example to include S3 storage configuration options.
- Updated main.go to initialize S3 client and handle audio uploads to S3.
- Modified processAudio function to return S3 URL when storage is enabled.
- Updated README.md with new S3 storage instructions and examples.

.env.example

@@ -2,7 +2,17 @@ PORT=4040
 CORS_ALLOW_ORIGINS=*
 API_KEY=429683C4C977415CAAFCCE10F7D57E11
 ENABLE_TRANSCRIPTION=true
-TRANSCRIPTION_PROVIDER=openai  # ou groq
-OPENAI_API_KEY=sua_chave_openai_aqui
-GROK_API_KEY=sua_chave_groq_aqui
-TRANSCRIPTION_LANGUAGE=pt
+TRANSCRIPTION_PROVIDER=openai  # or groq
+OPENAI_API_KEY=your_openai_key_here
+GROK_API_KEY=your_groq_key_here
+TRANSCRIPTION_LANGUAGE=en  # Default transcription language (optional)
+
+# S3 Storage Settings
+ENABLE_S3_STORAGE=true
+S3_ENDPOINT=play.min.io
+S3_ACCESS_KEY=your_access_key_here
+S3_SECRET_KEY=your_secret_key_here
+S3_BUCKET_NAME=audio-files
+S3_REGION=us-east-1
+S3_USE_SSL=true
+S3_URL_EXPIRATION=24h  # Duration format: 1h, 24h, 7d, etc.