V1 [TEST] Rate limiter integration test

[austin-barrington]

Context

Rate limiting is a V1 requirement (#62 tracks the bug where the rate limiter is broken). Once fixed, there must be an integration test.

Deliverables

Add an integration test at tests/integration/rate_limiter_test.rs:

1. Start server with rate_limit.enabled = true and max_requests_per_second = 5
2. Fire 5 rapid requests — all should succeed
3. Fire 5 more rapid requests — at least some should be rejected with HTTP 429
4. Wait 1 second
5. Fire 1 request — should succeed
6. Verify metrics endpoint shows hyperbytedb_rate_limit_denied_total > 0

References

• src/adapters/http/auth_middleware.rs:142-163 — rate limiter code (currently broken)
• #62 — rate limiter bug ticket

Priority

P2 — Test coverage after bug fix

[austin-barrington]

Fixed: Integration test in integration.rs:726-859 covers burst, denial (429), refill after 1.1s, and hyperbytedb_rate_limit_denied_total metric.