#8677: fix: add retry logic to OAuth token refresh

## Summary Adds retry logic with exponential backoff to the OAuth token refresh flow, preventing transient network/API failures from causing agent failures. ## Problem When `getOAuthApiKey()` fails transiently (network blip, API timeout), the gateway immediately throws without retrying. This causes agents to fail even when the issue is temporary and a simple retry would succeed. **Observed:** ``` 08:14:05 [agents/auth-profiles] wrote refreshed credentials to claude cli file 08:14:11 [diagnostic] OAuth token refresh failed for anthropic ``` Token had 8 hours remaining - the refresh API call itself failed. Gateway restart fixed it immediately. ## Solution Add `withRetry()` helper with exponential backoff (3 attempts: 1s, 2s, 3s delays) around the `getOAuthApiKey()` call. ## Changes - Add `withRetry<T>()` generic helper function - Wrap `getOAuthApiKey()` call in retry logic - Log warnings on retry attempts for debugging ## Testing The retry logic is straightforward and isolated. Existing tests should pass. The helper throws on final failure, preserving error semantics. Fixes #8673 <!-- greptile_comment --> <h2>Greptile Overview</h2> <h3>Greptile Summary</h3> Adds a small `withRetry<T>()` helper in `src/agents/auth-profiles/oauth.ts` to retry OAuth API key refresh with linear backoff (1s, 2s, 3s) for up to 3 attempts. The refresh flow now wraps `getOAuthApiKey()` in this retry logic to reduce transient network/API failures from immediately failing agents, while preserving the final error behavior on exhaustion. <h3>Confidence Score: 4/5</h3> - This PR is safe to merge with low risk; it adds localized retry/backoff around token refresh. - Change is confined to one file and wraps an existing network call without altering surrounding control flow; main concern is reduced observability in retry logs (stack/structured error details). - src/agents/auth-profiles/oauth.ts <!-- greptile_other_comments_section --> _{(2/5) Greptile learns from your feedback when you react with thumbs up/down!} <!-- /greptile_comment -->