fix(sway): use the us(dvorak) variant, not a "dvorak" layout

Dvorak is a variant of the "us" XKB layout, not a layout of its own:
there is no symbols/dvorak file, so "dvorak" fails to compile.

In the greetd/cage greeter the keymap comes solely from XKB_DEFAULT_*, so
the failure left the greeter with no keymap and therefore no keyboard
input at all (mouse unaffected). Split it into
XKB_DEFAULT_LAYOUT=us + XKB_DEFAULT_VARIANT=dvorak.

The same mistake in the Sway session (home/sway.nix) was masked: the
default us keymap compiled and the failing override was silently dropped,
so the session ran QWERTY despite the dvorak setting. Use xkb_variant
there too so it is actually Dvorak.

console.keyMap = "dvorak" (workstation.nix) is unaffected -- that is a
kbd console map, a separate subsystem where "dvorak" is valid.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lyrathorpe/home/sway.nix

@@ -26,7 +26,13 @@
       # Launcher: sway-launcher-desktop running inside a floating foot window.
       menu = "${pkgs.foot}/bin/foot --app-id=launcher ${pkgs.sway-launcher-desktop}/bin/sway-launcher-desktop";
 
-      input."type:keyboard".xkb_layout = "dvorak";
+      # Dvorak is a variant of the "us" layout, not a standalone layout --
+      # `xkb_layout = "dvorak"` fails to compile (no symbols/dvorak) and wlroots
+      # silently falls back to QWERTY. Use the variant.
+      input."type:keyboard" = {
+        xkb_layout = "us";
+        xkb_variant = "dvorak";
+      };
 
       window.commands = [
         {