fix: handle IPv6 waypoint addresses in service routing

[hudazaan]

What type of PR is this?

/kind bug

What this PR does / why we need it:

• This PR fixes IPv6 waypoint detection in the workload service routing path.
• The service waypoint check only considered IPv4 addresses before redirecting traffic to a waypoint. As a result, valid IPv6 waypoint entries were skipped when wp_addr.ip4 was zero, preventing IPv6 traffic from being routed through the configured waypoint.

Which issue(s) this PR fixes:
Fixes #1460

Special notes for your reviewer:

• The fix validates the waypoint address as non-zero regardless of IP family
• The check is applied consistently in the service, backend, and direct-backend waypoint paths
• Validation was performed with the BPF unit-test build flow:
  • bash test/bpf_ut/build_bpf_ut_tests.sh

Does this PR introduce a user-facing change?:

NONE

[Copilot]

Copilot was unable to review this pull request because the user who requested the review has reached their quota limit.

[kmesh-bot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by:
Once this PR has been reviewed and has the lgtm label, please assign supercharge-xsy for approval. For more information see the Kubernetes Code Review Process.

The full list of commands accepted by this bot can be found here.

Details

Needs approval from an approver in each of these files:

• OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[kmesh-bot]

Welcome @hudazaan! It looks like this is your first PR to kmesh-net/kmesh 🎉

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 39.47%. Comparing base (32fe3df) to head (706b6a6).
⚠️ Report is 3 commits behind head on main.
see 2 files with indirect coverage changes

---

Continue to review full report in Codecov by Harness.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update ae15e8a...706b6a6. Read the comment docs.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.