The outer goroutine per-node acquired a semaphore slot and held it while
collectNode spawned inner goroutines needing slots from the same semaphore.
With maxConc=5 and 5+ nodes, all slots were consumed by outer goroutines,
inner goroutines blocked forever, and Collect() never returned — permanently
consuming an HTTP MaxRequestsInFlight slot until the server stopped responding.
Remove the redundant outer semaphore acquire (inner goroutines already manage
their own slots) and add a 120s HTTP timeout as defense-in-depth.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
