Skip dual-stack bind tests when the host lacks IPv6

[kixelated]

Summary

The tcp_ipv6_is_dual_stack and udp_ipv6_is_dual_stack tests in rs/moq-native/src/bind.rs bind [::]:0 to verify the socket comes back dual-stack. On hosts without an IPv6 stack (some CI sandboxes and containers) that bind fails outright, before the dual-stack flag can even be checked, so the tests fail for an environmental reason rather than an actual bug.

This makes those two tests resilient: they now treat the address-family family of errors as a "no IPv6 here" signal and skip (printing a note) instead of failing. The dual-stack assertion only has meaning once a socket exists, so there's nothing to verify when IPv6 is absent.

Detected error conditions:

• EAFNOSUPPORT (97), EADDRNOTAVAIL (99), EPROTONOSUPPORT (93) on Unix
• WSAEAFNOSUPPORT (10047), WSAEADDRNOTAVAIL (10049), WSAEPROTONOSUPPORT (10043) on Windows
• ErrorKind::AddrNotAvailable / ErrorKind::Unsupported

The production udp/tcp bind helpers are unchanged: a relay that genuinely can't bind its configured address should still fail loudly. Only the tests relax.

Test plan

• cargo test -p moq-native --lib bind passes in this IPv6-less sandbox (the two IPv6 tests skip, udp_ipv4_still_binds passes).
• On a host with IPv6, the assertions run as before.

🤖 Generated with Claude Code

(Written by Claude)

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Generated by Claude Code

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ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 1c606dea-d120-4261-876e-e11d93e16334

📥 Commits

Reviewing files that changed from the base of the PR and between ead91b0 and 793cf6a.

📒 Files selected for processing (1)

• rs/moq-native/src/bind.rs

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Walkthrough

The test module in rs/moq-native/src/bind.rs gains a skip_if_no_ipv6 helper function that inspects a std::io::Error by checking its ErrorKind and a hardcoded list of raw OS error codes to determine whether the error indicates the host has no IPv6 support. Both udp_ipv6_is_dual_stack and tcp_ipv6_is_dual_stack are changed from unconditional .unwrap() calls to match expressions: on an IPv6-absence error they return early (skipping the test), and on any other error they panic with a targeted message.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the main change: making dual-stack bind tests skip when IPv6 is unavailable, which aligns with the core objective of the PR.
Description check	✅ Passed	The description is well-related to the changeset, providing clear context about why the tests needed modification, what errors are being handled, and verification that the fix works as intended.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

✨ Simplify code

• Create PR with simplified code
• Commit simplified code in branch claude/ipv6-dual-stack-resilience-l2qv9e

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