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>

agent/JOURNAL.md

@@ -19,6 +19,24 @@ Template:
 
 ---
 
+## 2026-07-11 — Night-light geo mode (lat/long → wlsunset)
+- **Task:** BACKLOG LATER "Night-light geo mode" (human-picked).
+- **Did:** `nomarchy.nightlight.latitude`/`.longitude` (both set = geo mode):
+  `services.wlsunset` (location-computed sunrise/sunset, `.temperature` →
+  night temp) replaces hyprsunset; the toggle script's `unit=` and the
+  live-state ExecCondition follow via one `unit` let-binding. Template
+  example lines, README row, ROADMAP ✓. New `checks.nightlight-geo`:
+  pure-eval asserts on the rendered units (coords + temp in ExecStart,
+  ExecCondition present, hyprsunset off). Declarative-only (no menu writer —
+  coords are machine config like keyboard layout).
+- **Verified:** V1 — `nix flake check --no-build` exit 0 (evals the new
+  asserts + option-docs); built `downstream-template-home` (default
+  hyprsunset path unregressed) + the check drv. Caught en route: HM renders
+  `ExecStart` as a list (`toString` needed in eval asserts).
+- **Pending:** V3 queued (HARDWARE-QUEUE § Any machine): visible warm shift
+  at location night + toggle/persistence on the swapped unit.
+- **Next suggestion:** wallpapers artifact split (LATER, decided).
+
 ## 2026-07-11 — Sync-sweep rule + grooming + zram user docs (human-requested)
 - **Task:** Bernardo: groom stale items and codify the check so they don't
   recur; close the zram user-doc gap.