## What changed
- Try the explicitly configured Windows HTTP or SOCKS5 proxy port first, then scan the protocol's preferred port range when that port is unavailable.
- Reserve HTTP and SOCKS5 listeners independently so a SOCKS5 collision does not replace an already available HTTP listener.
- Retain ephemeral loopback fallback when all preferred ports are unavailable, and document the HTTP (`3128-3159`) and SOCKS5 (`8081-8112`) ranges.
## Testing
- Cover bounded HTTP and SOCKS5 fallback, independent listener reservation, and ephemeral fallback after preferred-port exhaustion.
GitOrigin-RevId: 002c641f5bd70fedf04cca96c65c5fee2c5ebcac