Add sway/wofi/foot Wayland desktop stack with per-host toggle

New opt-in feature for x86_64 desktops: sway + wofi + foot + swaybg +
swaylock + swayidle + grim + slurp + waybar + wl-clipboard. mako on
arch, dunst on debian (mako isn't packaged for debian).

Files:
- .chezmoi.yaml.tmpl: added data.sway flag (true on miche/byte/kaiser,
  false on Pis). Override per host with ~/.config/chezmoi/features/sway
  or ~/.config/chezmoi/features/no-sway marker files.
- run_once_40-install-sway.sh.tmpl: installs packages if .sway=true,
  exits 0 otherwise. Sets up the marker file.
- dot_config/{sway,foot,wofi,waybar,mako}/: existing configs from miche.

Per-host toggle workflow:
  # On any box, enable sway:
  touch ~/.config/chezmoi/features/sway
  chezmoi apply

  # On a sway-enabled box, disable it:
  touch ~/.config/chezmoi/features/no-sway
  rm ~/.config/chezmoi/features/sway
  chezmoi apply

Currently sway packages are already installed on miche (existed before
this commit). Byte will get them via the new run_once_40 script.
Pis (rye, crouton) are unaffected — install script early-returns.

.chezmoi.yaml.tmpl

@@ -60,4 +60,22 @@ age:
 
 data:
     os_family: {{ $osFamily | quote }}
-    os_id: {{ .chezmoi.osRelease.id | quote }}
+    os_id: {{ .chezmoi.osRelease.id | quote }}
+
+    # Sway/Wayland desktop stack — enabled per host. Pis don't need it
+    # (headless); x86_64 desktops do. Override at runtime by creating
+    # `~/.config/chezmoi/features/sway` (force ON) or
+    # `~/.config/chezmoi/features/no-sway` (force OFF).
+    #
+    # To toggle for a new box: `touch ~/.config/chezmoi/features/sway`
+    # then `chezmoi apply`.
+    {{- $swayOverrideOn := stat (joinPath .chezmoi.homeDir ".config/chezmoi/features/sway") }}
+    {{- $swayOverrideOff := stat (joinPath .chezmoi.homeDir ".config/chezmoi/features/no-sway") }}
+    {{- if $swayOverrideOn }}
+    sway: true
+    {{- else if $swayOverrideOff }}
+    sway: false
+    {{- else }}
+    {{- $swayHosts := list "miche" "byte" "kaiser" }}
+    sway: {{ has .chezmoi.hostname $swayHosts }}
+    {{- end }}