spotify connector 연동

[kakasoo]

Test before submitting

Before submitting a Pull Request, please test your code. If you created a new created a new feature, then create the test function, too. Please refer to this document.

Put the name of the test function of the service you created in the command below.
This is a regular expression that returns all tests containing the character string, so if there are several test codes, you can put a keyword including all of the test codes and turn them.
If you omit the include statement and operate the test, all the test codes we write will work, and myriad errors will occur in your code without environmental variables.

npm run build && npm run test -- --include TEST_FUNCTION_NAME

Of course you won't be able to provide us with your environmental variables, so we'll replace them with our environmental variables to run the program and merge it depending on whether it passes or not.

Purpose

Please explain to our developers what the features you modified or developed are for.

Check List

• Passing an existing or newly created test
• sufficient summary and description for LLM to understand
• Does it ensure backward compatibility with existing features, or does the modifications not affect pre-modification request, response type?

[kakasoo]

Spotify 관련 기능이 추가된 점이 인상적입니다. 하지만 SpotifyProvider의 refresh 메서드에서 Base64 인코딩 관련 주석이 중복되어 간결하게 정리하면 좋을 것 같습니다. 또한, 에러 처리 시 민감한 정보가 노출되지 않도록 로깅 시스템을 활용하는 것을 고려해보세요.