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.

dot_config/sway/config.d/10-keybinds.conf

@@ -0,0 +1,76 @@
+# === ~/.config/sway/config.d/10-keybinds.conf ===
+# sway keybindings. Mint+Cinnamon muscle memory → Super (Mod4).
+
+# === essentials ===
+bindsym $mod+Return exec $term
+bindsym $mod+d exec $menu
+bindsym $mod+e exec $fileManager
+bindsym $mod+b exec $browser
+bindsym $mod+q kill
+bindsym $mod+Shift+c reload
+bindsym $mod+Shift+e exec swaynag -t warning \
+    -m 'Exit Sway?' \
+    -B 'Yes, exit Sway' 'swaymsg exit'
+
+# === move focus ===
+bindsym $mod+Left focus left
+bindsym $mod+Down focus down
+bindsym $mod+Up focus up
+bindsym $mod+Right focus right
+bindsym $mod+Shift+Left move left
+bindsym $mod+Shift+Down move down
+bindsym $mod+Shift+Up move up
+bindsym $mod+Shift+Right move right
+
+# === workspace navigation ===
+bindsym $mod+1 workspace number 1
+bindsym $mod+2 workspace number 2
+bindsym $mod+3 workspace number 3
+bindsym $mod+4 workspace number 4
+bindsym $mod+5 workspace number 5
+bindsym $mod+6 workspace number 6
+bindsym $mod+7 workspace number 7
+bindsym $mod+8 workspace number 8
+bindsym $mod+9 workspace number 9
+bindsym $mod+0 workspace number 10
+bindsym $mod+Tab workspace back_and_forth
+bindsym $mod+Shift+1 move container to workspace number 1
+bindsym $mod+Shift+2 move container to workspace number 2
+bindsym $mod+Shift+3 move container to workspace number 3
+bindsym $mod+Shift+4 move container to workspace number 4
+bindsym $mod+Shift+5 move container to workspace number 5
+bindsym $mod+Shift+6 move container to workspace number 6
+bindsym $mod+Shift+7 move container to workspace number 7
+bindsym $mod+Shift+8 move container to workspace number 8
+bindsym $mod+Shift+9 move container to workspace number 9
+bindsym $mod+Shift+0 move container to workspace number 10
+
+# === layout ===
+bindsym $mod+f fullscreen
+bindsym $mod+v split toggle splitv
+bindsym $mod+s layout stacking
+bindsym $mod+w layout tabbed
+bindsym $mod+space floating toggle
+bindsym $mod+Shift+space focus mode_toggle
+
+# === screenshot (grim + slurp) ===
+bindsym Print exec grim -g "$(slurp)" ~/Pictures/screenshot-$(date +%Y%m%d-%H%M%S).png
+bindsym $mod+Print exec grim ~/Pictures/screenshot-$(date +%Y%m%d-%H%M%S).png
+bindsym $mod+Shift+s exec grim -g "$(slurp)" - | wl-copy
+
+# === resize ===
+mode "resize" {
+    bindsym Left resize shrink width 30px
+    bindsym Down resize grow height 30px
+    bindsym Up resize shrink height 30px
+    bindsym Right resize grow width 30px
+    bindsym Escape mode "default"
+    bindsym Return mode "default"
+}
+bindsym $mod+r mode "resize"
+
+# === scratchpads (quick terminal / browser) ===
+# Start a headless foot server, then a dropdown client window. Toggle with $mod+grave.
+bindsym $mod+grave exec foot --server
+bindsym $mod+apostrophe exec foot -a dropdown
+for_window [app_id="dropdown"] floating enable, sticky enable, resize set width 1100 height 600, move position center