feat(s3): enhance logging and public URL generation

Add detailed logging for S3 uploads in user and content services. Improve public URL generation logic in `S3Service` by providing better handling for `API_URL`, `DOMAIN_NAME`, and `PORT`. Update relevant tests to cover all scenarios.

backend/src/contents/contents.service.ts

@@ -100,6 +100,7 @@ export class ContentsService {
 		// 3. Upload vers S3
 		const key = `contents/${userId}/${Date.now()}-${uuidv4()}.${processed.extension}`;
 		await this.s3Service.uploadFile(key, processed.buffer, processed.mimeType);
+		this.logger.log(`File uploaded successfully to S3: ${key}`);
 
 		// 4. Création en base de données
 		return await this.create(userId, {