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/foot/foot.ini

@@ -0,0 +1,88 @@
+# foot terminal — gruvbox dark, Maple Mono 14pt with Terminus fallback
+# Reference: man foot.ini
+
+[main]
+font=Maple Mono CN:size=14,Terminus:size=14
+font-bold=Maple Mono CN:weight=bold:size=14
+font-italic=Maple Mono CN:slant=italic:size=14
+font-bold-italic=Maple Mono CN:weight=bold:slant=italic:size=14
+font-size-adjustment=0.5
+pad=8x8
+term=foot
+# (Previously set to "foot-extra", but that terminfo is not installed in the
+# CachyOS foot package; only foot, foot+base, foot-direct are. Setting
+# TERM=foot-extra breaks every ncurses program — htop, nvtop, vim, etc. —
+# with "cannot initialize terminal type". "foot" has 256 colors and
+# everything modern tools need.)
+# kaiser runs zsh as the login shell (SHELL=/bin/fish was misleading — that
+# comes from sway's inherited env, not the user's actual shell). Hardcode
+# /usr/bin/zsh here. foot does NOT expand $SHELL in the shell= value (it
+# passes the literal string to its child), so don't try the sh,-c trick —
+# it just makes foot spawn a binary literally named "${SHELL:-/bin/bash}"
+# and exit with "No such file or directory".
+shell=/usr/bin/zsh
+
+# PTY
+# utmphelper is not packaged with foot on this CachyOS build. Leave it unset
+# to disable utmp logging for foot sessions; harmless and not required.
+
+# Initial geometry
+initial-window-size-chars=120x32
+
+[scrollback]
+lines=10000
+indicator-position=relative
+
+[cursor]
+style=block
+blink=yes
+blink-rate=500
+beam-thickness=2px
+
+[mouse]
+hide-when-typing=yes
+alternate-scroll-mode=true
+
+[colors-dark]
+# Gruvbox dark palette (gruvbox-community) — bg0_h / fg / 16 ANSI
+# https://github.com/gruvbox-community/gruvbox
+background=1d2021
+foreground=ebdbb2
+# Slight transparency — 0.90 alpha. Foot 1.27+ uses a separate alpha key
+# (in [colors-dark], not 8-digit hex — that was foot 1.24 syntax).
+alpha=0.90
+
+# Regular ANSI (0-7)
+regular0=282828
+regular1=cc241d
+regular2=98971a
+regular3=d79921
+regular4=458588
+regular5=b16286
+regular6=689d6a
+regular7=a89984
+
+# Bright ANSI (8-15)
+bright0=928374
+bright1=fb4934
+bright2=b8bb26
+bright3=fabd2f
+bright4=83a598
+bright5=d3869b
+bright6=8ec07c
+bright7=ebdbb2
+
+# Selection (FG BG pair)
+selection-foreground=1d2021
+selection-background=ebdbb2
+# Search box (FG BG pairs)
+search-box-match=ebdbb2 458588
+search-box-no-match=ebdbb2 cc241d
+
+[bell]
+urgent=no
+notify=no
+visual=no
+
+[url]
+launch=xdg-open {url}

dot_config/foot/patch.py

@@ -0,0 +1,25 @@
+from pathlib import Path
+p = Path("/home/rain/.config/foot/foot.ini")
+text = p.read_text()
+old_lines = [
+    "# foot does not expand env variables in the `shell=` value, so we have to",
+    "# go through `sh -c` to make the parent's $SHELL take effect. When foot",
+    "# is launched from a fish session, $SHELL is /bin/fish, and foot runs fish.",
+    "# When launched from bash, $SHELL is /bin/bash, and foot runs bash. The",
+    "# default fallback is /bin/bash if $SHELL is unset for any reason.",
+    'shell=sh,-c,"exec ${SHELL:-/bin/bash} -i"',
+]
+new_lines = [
+    "# kaiser runs zsh as the login shell. Hardcode /usr/bin/zsh here.",
+    "# foot does NOT expand $SHELL in shell= (it passes the literal string",
+    "# to its child process), so the sh,-c trick makes foot try to exec a",
+    '# binary literally named "${SHELL:-/bin/bash}" and die with',
+    '# "No such file or directory". Point shell= at the binary directly.',
+    "shell=/usr/bin/zsh",
+]
+old = "\n".join(old_lines)
+new = "\n".join(new_lines)
+assert old in text, "old block not found in foot.ini"
+text = text.replace(old, new, 1)
+p.write_text(text)
+print("OK, new size:", len(text))