feat(autotheme): fire at the configured sunrise/sunset, not a 15-min poll

The timer's OnCalendar now bakes the configured times (falling back
like _hhmm_to_min on a hand-edited state), so the switch lands at the
configured minute instead of up to 15 minutes late. The original
poll's robustness case is covered without it: Persistent catches
transitions missed while powered off, systemd fires elapsed calendar
timers on resume, and OnStartupSec settles the theme after login.

Baked times mean a time edit must rebuild: the menu's Sunrise/Sunset
writes now run `auto --force` when enabled (one rebuild re-bakes the
timer and lands on the right theme, same as the enable flow). Day and
night slugs stay live reads — but with no poll to catch them up,
editing the slot currently on screen applies immediately via a plain
`auto`. New eval check `auto-theme-timer` asserts the bake
state-bridges-style: configured times reach OnCalendar, garbage falls
back to 07:00/20:00, disabled installs no unit. Docs + hardware-queue
entry updated to the new semantics.

V2: checks.auto-theme (KVM VM, passed) covers the auto engine the
timer ticks; checks.auto-theme-timer (eval, passed) covers the unit;
OnCalendar strings systemd-analyze-validated; the rebuilt menu script
passes bash -n with the new branches in place. V3 pending: live timer
firing at the exact configured minute on hardware (existing
"Auto-theme pair flip" queue entry, refreshed).

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

agent/HARDWARE-QUEUE.md

@@ -52,11 +52,18 @@ Everything else below stays open; order is convenience, not a gate.
       summer-day; this is the on-hardware confirmation of the report.
 - [ ] **Auto-theme pair flip on hardware** — set
       `settings.autoTheme.{day,night}` to one of the new pairs (e.g.
-      kiln-clay / kiln), force sunrise/sunset around the current time,
-      let the timer flip once each way. Pass = the whole desktop switches
-      in one generation, and nothing leaks from the previous theme —
-      fonts, rounding, terminal opacity all reset (the per-theme
-      appearance block), wallpaper follows.
+      kiln-clay / kiln), set sunset (or sunrise) a few minutes ahead via
+      Look & Feel › Auto theme (the time edit itself rebuilds — since the
+      exact-time revision the timer fires AT the configured minute, no
+      15-min poll), let the timer flip once each way. Pass = (1)
+      `systemctl --user list-timers nomarchy-auto-theme` shows the two
+      configured times as the trigger; (2) the switch lands within ~a
+      minute of the configured time; (3) the whole desktop switches in
+      one generation, and nothing leaks from the previous theme — fonts,
+      rounding, terminal opacity all reset (the per-theme appearance
+      block), wallpaper follows; (4) with autoCommit on, `git -C
+      ~/.nomarchy log` shows an `apply theme` commit and state.json is
+      not left dirty (the 0.5.1 pathspec fix).
 - [ ] **#148 dock-intent enforcement without auto-profiles (dev box, docked)** —
       after pulling the #148 commit: **log out and back in first** — the
       watcher is `exec-once`, so `nomarchy-home` alone leaves the old one