feat(nightlight): geo mode — lat/long-computed sunset via wlsunset

Set BOTH nomarchy.nightlight.latitude/.longitude and the night light
switches backing unit: wlsunset computes sunrise/sunset from the
location daily (the fixed .sunrise/.sunset are ignored;
.temperature feeds the night temp). Everything user-facing is
unchanged — same nomarchy-nightlight toggle script, Waybar moon, and
live-state ExecCondition gate; the unit name is a single let-binding
so all three follow together. Declarative-only on purpose: coordinates
are machine config like the keyboard layout, so home.nix (commented
template example), not a menu writer.

checks.nightlight-geo guards the wiring at pure eval: rendered
wlsunset ExecStart carries the coords + night temperature, the
ExecCondition gate landed on the swapped unit, hyprsunset stays off in
geo mode.

Verification: V1 — nix flake check --no-build exit 0 (evals the new
asserts + option-docs sync); built downstream-template-home (default
hyprsunset path unregressed). V3 pending: visible warm shift at the
location's night + instant toggle/off-persistence on the swapped unit
(HARDWARE-QUEUE § Any machine).

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

README.md

@@ -233,7 +233,7 @@ two tables below are split along exactly that line.
 | `nomarchy.keyboard.variant` | `""` | XKB variant for the session |
 | `nomarchy.keyboard.devices` | `{}` | Per-device layout overrides (Hyprland `device` blocks keyed by `hyprctl devices` name) — e.g. an external keyboard with its own layout/variant |
 | `nomarchy.keyboard.layouts` | `[]` | Extra candidate layouts; when set, a watcher prompts (rofi) for a layout on a newly-connected keyboard and remembers it per-device |
-| `nomarchy.nightlight.enable` | `false` | Scheduled blue-light filter (hyprsunset) — warm at night (`.temperature`, default 4000K) between `.sunset`/`.sunrise`, no shift by day; off by default — enable it from the menu (System › Night light; the first enable rebuilds), then toggle on/off instantly from the menu or the Waybar moon indicator (writes `settings.nightlight.on` in your flake, no rebuild) and it survives reboot, so it stays reproducible |
+| `nomarchy.nightlight.enable` | `false` | Scheduled blue-light filter (hyprsunset) — warm at night (`.temperature`, default 4000K) between `.sunset`/`.sunrise`, no shift by day; set BOTH `.latitude`/`.longitude` for **geo mode** (wlsunset computes sunrise/sunset from your location; the fixed times are ignored); off by default — enable it from the menu (System › Night light; the first enable rebuilds), then toggle on/off instantly from the menu or the Waybar moon indicator (writes `settings.nightlight.on` in your flake, no rebuild) and it survives reboot, so it stays reproducible |
 | `nomarchy.updates.enable` | `false` | Passive update awareness: a background check (`.interval`, default daily) that flags when flake inputs (nixpkgs, the Nomarchy input, …) are behind upstream — and, with Flatpak on, when apps have updates (`.flatpak`) — via a Waybar indicator + notification. Never changes anything; click the indicator to run the upgrade flow |
 | `nomarchy.hyprland.enable` | `true` | Nomarchy's Hyprland config |
 | `nomarchy.waybar.enable` | `true` | Nomarchy's Waybar |