Fix test failures in parallel execution and add REFRESH_AES_KEY for token encryption

[kimitrii]

Changes Made

This PR introduces a new environment variable, REFRESH_AES_KEY, which will be used to encrypt Refresh Tokens. Additionally, it updates the Vitest configuration by setting singleWorker to true, ensuring that all tests run within a single process. This change resolves test failures that occurred when running in parallel across multiple workers.

Furthermore, the Hono and vitest-pool-workers packages have been updated to their latest versions.

Changes Type

• Config
• bug fix

Checklist:

• The changes do not generate new error logs or warnings.
• I have added tests that prove the fix or new feature works as expected.
• Both new and existing tests pass locally.