test(hibernate): #76 slice 3 — V2 hibernate→resume VM check (PASS)

Add checks.hibernate: a runNixOSTest modeled on nixpkgs' hibernate.nix,
wired to the actual risk #76 introduces — coexistence with the zram swap
that oom.nix now enables by default. It imports oom.nix, puts the disk
swap at a lower priority than zram with an explicit boot.resumeDevice,
and uses systemd-initrd. The test drives a full
hibernate -> power-off -> resume -> crash cycle: a volatile ramfs marker
survives resume but NOT a crash-boot (proving genuine resume), and it
asserts zram sits at priority 100 while the disk swap is lower, so the
hibernate image lands on disk rather than volatile zram.

What QEMU genuinely can't do — feed a boot-time resume_offset for a btrfs
swapfile (offset only exists after first-boot allocation) or drive a
LUKS-initrd unlock — stays a V3 laptop check (HARDWARE-QUEUE, dev box
already runs that exact layout), plus the no-swap notify in a real
session. With this, all V0/V1/V2 work on #76 is done; #76 collapses to a
[blocked:hw] stub and the design record moves to ROADMAP.

Verification: V2 PASS — nix build .#checks.x86_64-linux.hibernate built
the driver fresh and exited 0. nix flake check --no-build green.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

agent/JOURNAL.md

@@ -17,6 +17,24 @@ Template:
 
 ---
 
+## 2026-07-10 — #76 slice 3: hibernate VM test (V2 PASS) → #76 agent-complete
+- **Task:** BACKLOG #76 slice 3 — the mandatory V2 hibernate test + V3 queue.
+- **Did:** Added `checks.hibernate` (flake.nix), modeled on nixpkgs'
+  hibernate.nix but wired to Nomarchy's #76 risk: imports oom.nix (zram
+  default-on), disk swap at lower priority + explicit `boot.resumeDevice`,
+  systemd-initrd. Test drives hibernate→power-off→resume→crash: ramfs marker
+  survives resume, a crash-boot loses it (real resume, not a survivor), and
+  asserts zram@100 + disk-swap<100 so the image lands on disk not volatile
+  zram. Queued the V3 laptop steps (real LUKS+@swap+offset resume + no-swap
+  notify) in HARDWARE-QUEUE. Collapsed #76 to a `[blocked:hw]` stub; design
+  record → ROADMAP § "Hibernation + zram by default".
+- **Verified:** **V2 PASS** — `nix build .#checks.x86_64-linux.hibernate`
+  built the driver fresh and exited 0 (all assertions held). `nix flake
+  check --no-build` green.
+- **Pending:** only V3 (dev box / laptop) — #76's last check; close on PASS.
+- **Next suggestion:** #76 is now blocked:hw; NEXT head falls to LATER/
+  PROPOSED triage or a QA sweep — pick per LOOP.md orientation next session.
+
 ## 2026-07-10 — #76 slice 2: Hibernate notify-on-failure
 - **Task:** BACKLOG #76 remaining slice 2 — per the settled "keep row, notify
   on failure" call.