max_concurrent_per_repo=0 passes validation and stalls Git requests #79

Summary

server.max_concurrent_per_repo = 0 passes configuration validation but creates a semaphore with no permits, causing Git requests to wait indefinitely.

Current behavior

Validation accepts zero for the per-repository concurrency setting. The request middleware then constructs a zero-permit semaphore, so no request can acquire a permit and clients stall without useful progress or an immediate configuration error.

Expected behavior

Configuration validation should reject zero, or zero should have a clearly defined non-blocking meaning such as disabling the limit.

Suggested implementation

Require max_concurrent_per_repo to be greater than zero during validation and add a regression test for the invalid configuration. Rejecting zero is preferable unless an unlimited sentinel is intentionally documented and implemented.

Relevant code

• crates/walgit-config/src/lib.rs:1079
• crates/walgit-server/src/middleware.rs:147