feat(menu): Tailscale exit-node rows show country/city

The Exit node picker listed bare hostnames; Mullvad-style nodes are
meaningless without their location. Rows are now
"hostname  — Country City", sliced from `tailscale exit-node list` by
the header's fixed-width column offsets (COUNTRY/CITY can be
multi-word, so field splitting is wrong by construction); nodes without
a location stay a bare hostname, and the pick strips back to the
hostname at the first space before `tailscale set --exit-node`.

Closes BACKLOG LATER "VPN exit-node richer display"; the VPN
HARDWARE-QUEUE entry now covers the location rows.

Verification: V1 — the awk was proven against a fabricated fixture
(one-word city, multi-word "United States / New York, NY", bare
self-hosted node), flake check exit 0, downstream-template-home builds
(writeShellScriptBin syntax-gates the script). Real `tailscale
exit-node list` output stays V3 (existing VPN menu live-paths entry).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

agent/BACKLOG.md

@@ -65,7 +65,6 @@ HARDWARE-QUEUE. Close #76 on PASS.
   impermanence, BIOS/legacy boot.
 - **Boot-from-snapshot**: a systemd-boot equivalent of grub-btrfs.
 - **MIPI/IPU software-ISP camera** support (no-UVC machines).
-- **VPN exit-node richer display** (country/city) (optional).
 - **NixOS release bump → v2** `[human]`: deliberate, hand-edited, never
   automated; the previous attempt was discarded (2026-06-22) over a
   Hyprland OOM blocker — see MEMORY.md before retrying (NOW#3 should