Fix network status and latency on IPv6-only links

[emanueleadelini]

On a link with a usable IPv6 default route but no ordinary IPv4 route, omarchy-network-status can report disconnected or show failed IPv4 probes while IPv6 works. This addresses the status and latency portion of #11215, reported by @anomalousmouse.

The command now shares route selection between status and verbose output, preferring native IPv6 when IPv4 is absent or uses an IPv6 next hop / an IPv4 service-continuity source (192.0.0.0/29). Ordinary IPv4 and dual-stack links keep their IPv4 preference; an existing IPv4 route is retained if IPv6 is unavailable.

• Read the selected route's source, matching prefix and gateway, including via.host.
• Use an IPv6 Internet probe for an IPv6 route and scope link-local gateway probes to the interface.
• Preserve empty samples when ping fails.
• Give IPv6 address/gateway values separate rows and elide long values without changing the full text copied to the clipboard.

Related: #8683 adds separate IPv6 detail fields. This change focuses on selecting a usable route before the IPv4-only early return; it does not add parallel address fields.

Validation

• 14 regression scenarios pass, covering IPv4, dual-stack, IPv6-only, transition routes, source/prefix selection, scoped gateways, unanswered probes and offline state. The same test fails on the unmodified base at the IPv6 connected-status check.
• Real veth interfaces, kernel routes and ICMP replies in isolated Linux namespaces: five scenarios pass on both Linux and an Omarchy VM. Original and candidate scripts were compared against the same network setup.
• Running Omarchy 4.0.2-1 desktop: inspected before/after screenshots, including a long IPv6 address. The candidate command and Panel.qml were exercised; packaged files were restored after capture.
• test/all run on base b5589fa and this candidate in identical headless VM environments: CLI suite passes in both; the same four shell test files fail in both, with no added failures. The affected files are locate-test.sh, network-qr-test.sh, snapper-test.sh (missing omarchy-iso fixture), and ssh-reconnect-test.sh. This is not a claim that the full suite passes.
• Existing network-test.sh, Bash syntax and git diff --check pass.

Reproduction harness, results and environment notes. The isolated peer owns the probe addresses locally: these checks do not validate an ISP, Wi-Fi hardware, NAT64 or a complete 464XLAT deployment. omarchy-network-speedtest is outside this patch's scope, so #11215 should remain open for the remaining work.

Desktop before / after (isolated IPv6 backend)

Before: a reachable IPv6-only link is shown as disconnected.

After: connected status, IPv6 address, gateway and successful local probes; long values fit the panel. The local-peer latency is not an Internet performance measurement.

Prepared with AI assistance (Codex), by Emanuele Adelini · AD Next Lab.