Detect Podman netavark management bridges

[orrious]

Summary

Detect the actual Linux bridge backing a Podman netavark management network instead of assuming Docker's generated br-<id> naming convention.

• read netavark's network_interface field from the raw network inspect response
• fall back to Podman's libpod network endpoint when the compatibility response omits that field
• retain Docker bridge-name handling as the final fallback
• preserve current behavior for non-bridge Docker networks
• document the fix in the release notes

Validation

• Linux Go 1.26.5: go test ./runtime/docker

[orrious]

Rebased this branch onto current main, added the missing release-note entry, and force-pushed the updated head.

Current head: ccf195fef

Validation completed on the real lab runners:

• x86 runner: go test ./runtime/docker passed
• ARM runner: go test ./runtime/docker passed