fix: resolve race condition in token refresh interceptor (#20)

[Senthil455]

Description

Moves the original._retry = true flag before the
efreshPromise check in the axios response interceptor to fix a race condition when multiple requests receive 401 simultaneously.

Root Cause

When two API calls get a 401 at the same time:

• Request A enters the interceptor, finds no refreshPromise, sets _retry = true, creates refreshPromise
• Request B enters the interceptor, finds refreshPromise exists, awaits it, gets the token, retries
• Request B's _retry was never set to true
• If the retry also returns 401, Request B enters the interceptor again with _retry still undefined
• This causes the retry to attempt a new refresh, creating a loop

Changes

• Moved original._retry = true before the refreshPromise check in rontend/src/lib/api.ts
• Both the initial request and concurrent requests now properly mark themselves as retried

Testing

Existing refresh flow continues to work. The fix prevents the infinite loop scenario under concurrent 401 conditions.

Fixes #20

[Senthil455]

Code review looks good. The key fix is moving \original._retry = true\ before the
efreshPromise\ check, which eliminates the race window where two concurrent refresh attempts could both pass the guard.