api_request now retries HTTP 429 responses instead of failing immediately:
- Parse and honor a valid Retry-After header (seconds or HTTP-date).
- Fall back to full-jitter capped exponential backoff when the header is
missing or invalid.
- Bound retries by max_retries and delay by max_delay (env-overridable via
GITEA_MAX_RETRIES / GITEA_RETRY_BASE_DELAY / GITEA_RETRY_MAX_DELAY) — no
infinite loops.
- Non-429 errors and successful responses are unchanged.
Sleep, randomness, and clock are injectable so retry timing is tested
deterministically. Adds tests/test_retry_backoff.py (23 cases).
Closes#27
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
