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/lock-fancy.sh

@@ -0,0 +1,34 @@
+#!/bin/bash
+# lock-fancy.sh — fancy swaylock: snapshot the screen, dim+blur it, and use as background.
+# grim + ffmpeg (both already installed). No swaylock-effects overlay needed.
+
+set -e
+
+TMP=/tmp/lock-bg-483833.png
+DIM=/tmp/lock-bg-dim-483833.png
+
+# Snapshot the current screen
+grim -t png "$TMP" 2>/dev/null
+
+# Dim + blur via ffmpeg (much faster than ImageMagick)
+if [ -f "$TMP" ] && command -v ffmpeg >/dev/null; then
+    ffmpeg -loglevel error -y -i "$TMP"         -vf "boxblur=12:1,eq=brightness=-0.30:saturation=0.6"         -frames:v 1 "$DIM"
+    IMG="$DIM"
+else
+    # Fallback to the regular wallpaper
+    IMG="$HOME/.local/share/wallpapers/teach-invaders-gruvbox.png"
+fi
+
+# Launch swaylock
+swaylock -f -i "$IMG" \
+    --indicator-radius 100 \
+    --indicator-thickness 6 \
+    --ring-color ebdbb2 \
+    --inside-color 1d202180 \
+    --key-hl-color fe8019 \
+    --bs-hl-color fb4934 \
+    --text-color ebdbb2 \
+    --separator-color 00000000 \
+    --fade-in 0.3
+
+rm -f "$TMP" "$DIM" 2>/dev/null