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.

agent/BACKLOG.md

@@ -123,36 +123,6 @@ the measured number, both ISOs built from one tree), installs successfully with
 a network in a QEMU run, says clearly at boot that it needs one, and leaves the
 offline ISO's behaviour untouched (`checks.*` for the offline path stay green).
 
-### 115. Suspend-then-hibernate, with a way to set it up
-
-Bernardo, 2026-07-14: a suspended laptop should be able to fall through to
-hibernate after a while, so a bag-carried machine stops draining, and setting
-that up must be easy — not a systemd-sleep man-page trip.
-
-The mechanism is `systemd`'s `suspend-then-hibernate` plus
-`HibernateDelaySec`; the work is the surfacing, and the constraints are
-already in the tree. Hibernate needs the resume offset + swap the installer
-detects (`resumeOffset`/`rootUuid` in patch-template.py) — on a machine
-without them this must self-gate, not fail at suspend time, the way Battery
-limit gates on a battery. `modules/nixos/default.nix` already declines to
-hyprlock before an encrypted hibernate (the LUKS resume gates it); check that
-reasoning still holds when the suspend leads to hibernate. Menu placement: it
-belongs with the power settings, not the root (§ menu placement convention).
-
-Settle first (`[human]`): whether the delay is a preset list (30 min / 1 h /
-2 h / never) or a free-form entry, and whether it applies on battery only or
-always — the same on-AC question `modules/home/idle.nix`'s suspend listener
-already answers with `${onAc} ||`.
-
-In-flake state like the rest (`settings.*`), menu-writable, and read via
-`state-read.nix` on the NixOS side — NOT `config.nomarchy.settings`,
-which does not exist there (ROADMAP § *NixOS-side state bridges (#116)*; copy
-the `bluetooth.enable` shape in `modules/nixos/default.nix` and add a case to
-`checks.state-bridges`). Pass = the toggle survives a rebuild,
-a suspended machine hibernates after the configured delay and resumes, and a
-machine without hibernate support hides the row instead of offering a
-suspend that never wakes.
-
 ## LATER
 
 - **Wallpapers artifact split** (ROADMAP § Faster switches — decided,