feat: keymap/locale + form factor in installer; nm-applet visible by default

- Installer prompts for keyboard layout (with optional variant) and locale
  via curated short list + Other… fallback into the full localectl list;
  applies to the live session immediately (loadkeys + hyprctl) so the
  rest of the install types correctly. Generated system.nix emits
  console.keyMap, i18n.defaultLocale, and services.xserver.xkb.{layout,
  variant}.
- New nomarchy.{system,}.formFactor enum (laptop|desktop, default laptop).
  Installer auto-detects via /sys/class/power_supply/BAT* and lets the
  user flip the answer. Waybar drops the battery widget on desktop;
  battery-monitor service is gated on the same option.
- Lift waybar tray out of the collapsed group/tray-expander in the default
  theme so nm-applet's icon is visible without expanding the drawer.
- Live ISOs (TTY + graphical) get baseline mkDefault keyMap/locale so the
  installer's runtime override always wins.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

features/desktop/waybar/default.nix

@@ -15,14 +15,31 @@ let
   # Selected files
   configFile = if hasThemeConfig then (themeDir + "/config.jsonc") else defaultConfig;
   styleFile = if hasThemeStyle then (themeDir + "/style.css") else defaultStyle;
-  
+
+  rawSettings = builtins.fromJSON (builtins.readFile configFile);
+
+  # Modules that only make sense on a laptop. Filtered out of any
+  # `modules-*` slot when nomarchy.formFactor != "laptop" so a desktop
+  # build doesn't ship a permanently-empty battery indicator.
+  laptopOnlyModules = [ "battery" "custom/battery" ];
+  filterModules = mods:
+    if config.nomarchy.formFactor == "laptop"
+    then mods
+    else builtins.filter (m: !(builtins.elem m laptopOnlyModules)) mods;
+
+  settings = rawSettings // {
+    modules-left   = filterModules (rawSettings.modules-left   or []);
+    modules-center = filterModules (rawSettings.modules-center or []);
+    modules-right  = filterModules (rawSettings.modules-right  or []);
+  };
+
 in
 {
   programs.waybar = {
     enable = lib.mkDefault true;
     systemd.enable = lib.mkDefault true;
-    
-    settings = lib.mkDefault [ (builtins.fromJSON (builtins.readFile configFile)) ];
+
+    settings = lib.mkDefault [ settings ];
     style = lib.mkDefault (builtins.readFile styleFile);
   };