Shadow

[turuslan]

• open ipv6 udp socket lazily (shadow doesn't support ipv6)

[Copilot]

Pull Request Overview

This PR modifies the QUIC transport to support environments that don't have IPv6 support (specifically Shadow simulator) by lazily opening UDP sockets instead of creating them upfront during construction.

• Changed socket initialization from eager (constructor) to lazy (on-demand during dial)
• Updated makeClient method to return a result type and handle socket opening errors
• Modified client initialization to check for null clients and create them as needed

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/transport/quic/transport.cpp	Implements lazy socket creation with error handling and removes eager IPv4/IPv6 client initialization
include/libp2p/transport/quic/transport.hpp	Updates method signature to return result type for error handling

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