Replace process-liveness/log-scraping heuristics with Tailscale's
authoritative backend state published as status.json.
- UI now uses BackendState + Self.Online so "no Internet" no longer
shows Connected; surfaces the real Tailscale IP, node and tailnet.
- Auth key is auto-cleared from the UI after a successful keyed login
via a sentinel file picked up by param_bridge (non-acap3 variants).
- Run scripts background `tailscale up` and publish status every 5s so
re-auth (NeedsLogin + AuthURL) surfaces without starving the loop.
- Ported across aarch64, aarch64_ROOT, arm, arm_ROOT, and arm_acap3
(acap3 uses the status.json detection; it has no auth-key param).
- Bump bundled Tailscale binaries to 1.98.4 for all variants.
- Fix CONTRIBUTING.md issue/discussion links to this repo.
- Add packaging/wrapper copyright to LICENSE.