docs(agent): #76 hibernation design calls settled

Bernardo's three design calls on the hibernation half of #76:
- swap sizing = exactly RAM (installer default, no change)
- migration for existing machines = docs runbook (MIGRATION.md), not a tool
- no-swap Hibernate = keep menu row, notify on failure

Recon confirmed new installs are already hibernation-ready (installer +
patch-template resume wiring + Power-menu Hibernate row). Folded decisions
into BACKLOG #76; re-sliced remainder to MIGRATION.md runbook + notify-on-
failure menu; recorded in Decisions.

Verification: V0 (docs-only) nix flake check --no-build green.

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

agent/JOURNAL.md

@@ -17,6 +17,21 @@ Template:
 
 ---
 
+## 2026-07-10 — #76 hibernation design calls (no commit yet → this bookkeeping)
+- **Task:** BACKLOG #76 design slice — Bernardo made the open calls.
+- **Did:** Recon showed the hibernation half is **already built for new
+  installs** (installer defaults swap=RAM hibernation-ready `@swap` swapfile;
+  `patch-template.py` writes swapDevices/resumeDevice/resume_offset; Power
+  menu Hibernate row + LUKS/hyprlock handling exist). Settled 3 calls:
+  (1) swap sizing = **exactly RAM** (no change); (2) migration = **docs
+  runbook in MIGRATION.md**, not a tool; (3) no-swap Hibernate = **keep row,
+  notify on failure**. Folded into BACKLOG #76 (design ✓, re-sliced remaining:
+  MIGRATION.md runbook + notify-on-failure menu) and Decisions.
+- **Verified:** **V0** — `nix flake check --no-build` green (docs-only).
+- **Pending:** two remaining slices below; V2 hibernate VM test + V3 laptop.
+- **Next suggestion:** slice 1 — `docs/MIGRATION.md` hibernation-enable runbook
+  (V0), then slice 2 — Hibernate notify-on-failure (V1/V2).
+
 ## 2026-07-10 — #76 zram slice: compressed-RAM swap default
 - **Task:** BACKLOG #76 (`[big]`) — split; took the low-risk zram-default slice.
 - **Did:** `zramSwap` on by default in `modules/nixos/oom.nix` (zstd, 50% RAM,