fix(install): normalize empty keyboard variants

Treat the picker-only (none) row as an empty XKB variant at the shared input boundary and again in the template patcher. Guard the real downstream output and console keymap, and carry the sentinel through the offline installer VM.

Verified: V0 full flake evaluation plus shell/Python/Nix/diff checks; V1 installer-keyboard, installer-safety, and template-SoT builds; V2 full KVM offline LUKS+swap install and themed first boot. No V3 required.

agent/JOURNAL.md

@@ -19,6 +19,21 @@ Template:
 
 ---
 
+## 2026-07-13 — #91 installer no-variant normalization (this commit)
+- **Task:** Stop the keyboard picker's display-only `(none)` value from
+  breaking generated `xkb-console-keymap.drv` and the whole installation.
+- **Did:** Normalize at the shared input boundary and defensively in the real
+  template patcher. Added a `us` + sentinel fixture, actual console-keymap
+  build, and made the offline installer VM carry the literal sentinel.
+- **Verified:** V2 — full flake eval; focused installer-keyboard/safety/
+  template builds; shell/Python/Nix syntax and diff checks; KVM
+  `tools/test-install.sh` installed offline with LUKS + swap, powered off after
+  ~400s, unlocked, and booted the themed desktop. Inspected install progress,
+  LUKS, and first-boot captures under `/tmp/nomarchy-vm/`.
+- **Pending:** #92 now explicitly forbids free-form XKB values. Expanded the
+  existing per-device keyboard hardware check for the connected-at-login menu.
+- **Next suggestion:** #92 installer keyboard selection clarity/safety.
+
 ## 2026-07-13 — #101 charge-limit AC-event burst recovery (this commit)
 - **Task:** Fix `nomarchy-battery-charge-limit.service` failing when USB-C
   dock power events arrive while its settling write is still active.