fix(install): label and explain the swap-size prompt

BACKLOG #93 (Acer live pass): the swap field appeared as a bare
prefilled number — gum never renders the placeholder once --value is
set, and the block had no section header, so nothing said what the
value meant. Add a visible "Swap & hibernation" section, two info lines
(default = RAM keeps hibernation possible; 0 = no swap), a labeled
--header on the input, and make the info + Review lines state the
outcome in full ("N GiB swapfile (enables hibernation)" /
"none (hibernation disabled)"). Default behavior unchanged (swap = RAM).

Verified: V2 — interactive KVM UI drive of the built ISO; viewed
10-swap-prompt.png (section + explanations + labeled input) and the
Review box ("Swap: 6 GiB swapfile (enables hibernation)") in
/tmp/nomarchy-v2-swap-93/; the wipe confirmation was aborted, nothing
touched. bash -n + nix flake check --no-build green.

Side-finding recorded on #112: QEMU's /dev/fd0 was listed first by the
disk picker (live repro evidence in the same artifacts).

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

agent/JOURNAL.md

@@ -19,6 +19,23 @@ Template:
 
 ---
 
+## 2026-07-13 — #93 installer swap prompt labeled + explained (this commit)
+- **Task:** BACKLOG #93 — the swap field was a bare prefilled gum input (no
+  visible section, label, or unit; the placeholder never shows once a value
+  is prefilled).
+- **Did:** `nomarchy-install.sh`: visible "Swap & hibernation" section, two
+  info lines (default = RAM ⇒ hibernation-ready; 0 = no swap), a labeled
+  `--header` on the input, and unambiguous info + Review lines
+  ("N GiB swapfile (enables hibernation)" / "none (hibernation disabled)").
+- **Verified:** V2 — full interactive KVM UI drive on the built ISO; VIEWED
+  `/tmp/nomarchy-v2-swap-93/10-swap-prompt.png` (section, both info lines,
+  labeled prefilled input) and `…/30-doctor.png` (Review box:
+  "Swap: 6 GiB swapfile (enables hibernation)"); wipe confirm aborted by
+  mismatch, nothing touched. bash -n + V0 flake check green.
+- **Pending:** side-finding: QEMU exposed `/dev/fd0` as the FIRST picker row
+  — recorded as live repro evidence on #112.
+- **Next suggestion:** #99/#107 commits from the same evidence run.
+
 ## 2026-07-13 — charge-limit start-limit-hit on spaced AC storms (this commit)
 - **Task:** Live V3 failure of #101 (TuringMachine doctor badge, 18:16): a
   spaced dock/AC event storm → 5 successful starts in 10s →