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/swaywm.nix

@@ -52,13 +52,17 @@ in
     # features.swayDesktop (e.g. EDaaS) keep plain TTY login.
     programs.regreet.enable = true;
     # cage reads the XKB_* environment at startup, so force the greeter onto the
-    # same Dvorak layout as the console (workstation.nix) and the Sway session
-    # (home/sway.nix) -- otherwise the password field would be QWERTY. This
-    # overrides the greetd command regreet sets with mkDefault.
+    # same Dvorak layout as the Sway session (home/sway.nix) -- otherwise the
+    # password field would be QWERTY. Dvorak is the "us" layout's variant, NOT a
+    # layout of its own: "dvorak" alone has no symbols/ file, so the keymap
+    # fails to compile and the greeter ends up with no keyboard at all (the
+    # greeter has no fallback, unlike a running Sway session). This overrides the
+    # greetd command regreet sets with mkDefault.
     services.greetd.settings.default_session.command =
       let
         greeter = pkgs.writeShellScript "regreet-cage" ''
-          export XKB_DEFAULT_LAYOUT=dvorak
+          export XKB_DEFAULT_LAYOUT=us
+          export XKB_DEFAULT_VARIANT=dvorak
           exec ${pkgs.dbus}/bin/dbus-run-session ${lib.getExe pkgs.cage} -s -- ${lib.getExe config.programs.regreet.package}
         '';
       in