V1 [TEST] Proxy integration tests

[austin-barrington]

Context

The hyperbytedb-proxy crate exists in the workspace but has no integration tests. The proxy provides TLS termination, load balancing, query routing, and health checking.

Deliverables

Add a test suite for the proxy at hyperbytedb-proxy/tests/. Test scenarios:

1. Start a mock backend (or real hyperbytedb server) on a known port
2. Start the proxy configured to forward to the backend
3. Send requests through the proxy and verify they reach the backend
4. Backend health check reporting
5. Backend failure and recovery (stop/start the backend)
6. TLS termination (if proxy is configured with TLS)
7. Stale backend detection and removal from load balancer

Use tokio::time::pause where appropriate to speed up health-check intervals.

References

• hyperbytedb-proxy/ — proxy crate structure
• hyperbytedb-proxy/src/main.rs — proxy entry point

Priority

P2 — Test coverage, component integration