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.

templates/downstream/flake.nix

@@ -4,9 +4,12 @@
   # The only input. nixpkgs, home-manager etc. come pinned through it —
   # tested together upstream. This file is written once (by you or the
   # installer) and never hand-edited afterwards; your machine lives in
-  # system.nix and home.nix. v1 is the release branch.
-  # Installer copies this template and patches username + hardwareProfile.
-  inputs.nomarchy.url = "git+https://git.bemagri.xyz/bernardo/nomarchy.git?ref=v1";
+  # system.nix and home.nix.
+  # Development tip is `main`. Release consumers pin `?ref=v1` once that
+  # pointer is current (installer overwrites this URL from the ISO build).
+  # Installer copies this template and patches username + hardwareProfile
+  # + the nomarchy input URL.
+  inputs.nomarchy.url = "git+https://git.bemagri.xyz/bernardo/nomarchy.git?ref=main";
 
   outputs = { nomarchy, ... }:
     nomarchy.lib.mkFlake {