feat(launcher): add IPv6 connectivity via local UDP proxy for SA:MP compatibility

[Knogle]

Ahoy, hope you guys are doing fine.

This PR adds practical IPv6 support to the launcher flow, including compatibility with the samp.dll layer that is still IPv4-only.

• Adds an internal local UDP proxy in the launcher (src-tauri) for IPv6 targets.
• On IPv6 connect, the launcher now:
  • starts a local IPv4 endpoint (<local-ip>:<random-port>),
  • passes that local endpoint to gta_sa.exe / samp.dll,
  • relays traffic to the real remote IPv6 server.
• Integrates proxy start/stop in both:
  • normal launcher flow (UI connect),
  • CLI launch flow.
• Includes packet translation logic for SA:MP/RakNet compatibility, including legacy cipher/port remap handling where needed.

Why

omp-launcher can already resolve/query IPv6, but actual connect failed because samp.dll only uses an IPv4 stack.
This proxy bridge keeps the client-side behavior IPv4-local while enabling real IPv6 transport externally.

Result

• First real IPv6 connect through launcher + client stack is working end-to-end.
• Expected behavior: in some places the client may display the local proxy IP/port instead of the remote IPv6 endpoint.

Notes

• This is an initial/preliminary implementation focused on reliable connectivity.
• Additional hardening (strict loopback binding, stronger endpoint locking, timeout/abort refinements) can follow in a separate PR.

Also see:

openmultiplayer/RakNet#31