feat(power): suspend-then-hibernate 1h on battery (#115)

Human decision: 1h delay, battery only, Preferences enable/disable.
Wire systemd suspend-then-hibernate + HibernateDelaySec=1h +
HibernateOnACPower=false when settings.power.suspendThenHibernate is on
and boot.resumeDevice is set. Lid: s2h undocked, plain suspend on AC.
nomarchy-suspend for hypridle + Power menu (live state). LUKS unlock
before encrypted hibernate so s2h→disk is not double-password.
state-bridges assert the policy; HARDWARE-QUEUE #115 + suggested order.

V1: nix flake check --no-build. V3: bag-carry on hardware.

docs/ROADMAP.md

@@ -432,6 +432,15 @@ Design/decision records and a running log of shipped work (items marked
   sheet hardcodes near-black button text → black-on-dark in GTK dialogs
   (Boreal). Fix: force `adw-gtk3-dark` / `adw-gtk3` from palette mode,
   prefer-dark, and pin dialog button colours in Stylix extraCss.
+- ✓ **Suspend-then-hibernate (#115):** human decision — **1h** delay, **battery
+  only**, Preferences enable/disable. Mechanism: `suspend-then-hibernate` +
+  `HibernateDelaySec=1h` + `HibernateOnACPower=false`; lid
+  `HandleLidSwitch=suspend-then-hibernate` /
+  `HandleLidSwitchExternalPower=suspend` when on and `boot.resumeDevice` set.
+  State: `settings.power.suspendThenHibernate` (default on). Live path:
+  `nomarchy-suspend` (hypridle + Power menu). LUKS: unlock session before
+  encrypted hibernate phase so resume is LUKS-only (not hyprlock twice).
+  Menu row self-gates on CanHibernate. V3: HARDWARE-QUEUE bag-carry test.
 - ✓ **Generation prune (#128):** weekly `nomarchy-gen-prune` (system + HM):
   delete only gens older than **14 days** that are also beyond the **3 most
   recent past** gens (current always kept). Stock `nix.gc` no longer uses