fix(install): bake dconf, seed main, name ISO, display modes (#123–#126)

Batch of existing-bug fixes from Acer/XPS install findings:

- #123: HM pre-activate creates /run/user/$UID and prefers
  dbus-run-session so dconf no longer aborts the desktop bake
- #124: main-built ISOs seed ?ref=main; patch-template rewrites
  inputs.nomarchy.url from NOMARCHY_FLAKE_URL (was set but unused)
- #125: image.baseName → nomarchy-live-….iso (not nixos-live-…)
- #126: Display mode list sorted by pixel area; toast shows hyprctl
  size; TESTING notes QEMU fixed-window scaling illusion

Verified: V0 flake check, installer-safety, baseName eval, patch-template
flakeUrl rewrite, mode-sort fixture.

docs/ROADMAP.md

@@ -404,6 +404,13 @@ Design/decision records and a running log of shipped work (items marked
   decision rather than a drive-by. Proved to fail: dropping snapshot makes it
   name the missing entry. **V3 pending** — that the apps *launch* needs real
   hardware (HARDWARE-QUEUE, Acer M5-481T).
+- ✓ **Install fix batch (#123–#126):** (123) HM pre-activate creates
+  `/run/user/$UID` + `dbus-run-session` so dconf no longer aborts the bake;
+  (124) main-built ISOs seed `?ref=main` and installer actually rewrites
+  `inputs.nomarchy.url` from `NOMARCHY_FLAKE_URL` (was set but unused);
+  (125) `image.baseName` → `nomarchy-live-….iso`; (126) Display mode list
+  sorted by pixel area + toast reports hyprctl size; TESTING notes QEMU
+  fixed-window scaling. V3: reinstall on Acer/XPS for #123.
 - ✓ **Kitty is the only terminal (#95 complete):** Ghostty’s OpenGL 4.3 floor
   broke SUPER+Return (and classed doctor/calendar windows) on Ivy Bridge
   HD 4000 (Acer M5-481T). Maintaining two terminals was pure complexity.