feat(keymap): route installer layout choice into Hyprland's Wayland session

core/home/config/nomarchy/default/hypr/input.conf hardcoded
`kb_layout = us`, so the installer's services.xserver.xkb.layout and
console.keyMap writes (both set from the installer's KEYMAP_LAYOUT
prompt) only reached XWayland apps and the TTY console. Native-Wayland
apps — i.e. almost everything in a Nomarchy desktop — fell back to US
regardless of what the user picked. Surprising for any non-US user.

Path (a) from the Later row:

  - Added nomarchy.keymap.{layout,variant} to core/home/options.nix
    (defaults "us" / "").
  - Deleted the static input.conf from the bulk nomarchy/ deploy.
  - Replaced it with an explicit
    xdg.configFile."nomarchy/default/hypr/input.conf".text in
    core/home/configs.nix that interpolates the option values into
    kb_layout / kb_variant.
  - Installer's home.nix heredoc now writes
      nomarchy.keymap = { layout = "$KEYMAP_LAYOUT"; variant = "$KEYMAP_VARIANT"; };
    alongside nomarchy.formFactor, so the layout reaches Hyprland
    consistently with system.nix's xkb.layout / console.keyMap.

Documented in docs/OPTIONS.md (new `nomarchy.keymap.layout` /
`nomarchy.keymap.variant` entry). `nix flake check --no-build` clean.

installer/install.sh

@@ -1718,6 +1718,15 @@ EOF
   # Gates UI affordances like the waybar battery widget.
   nomarchy.formFactor = "$FORM_FACTOR";
 
+  # Keyboard layout for Hyprland's native Wayland session. system.nix
+  # writes services.xserver.xkb.layout (XWayland) and console.keyMap
+  # (TTY) to the same value, but Hyprland reads its own input config so
+  # this option needs to be set independently.
+  nomarchy.keymap = {
+    layout = "$KEYMAP_LAYOUT";
+    variant = "$KEYMAP_VARIANT";
+  };
+
   # User-level packages (Home Manager).
   #
   # Nomarchy already ships a minimal desktop (firefox, thunar, mpv, imv, mako,