feat(terminal): Kitty only — drop Ghostty (#95)

Ghostty's OpenGL 4.3 floor broke the Acer (HD 4000 / 4.2). Dual-terminal
support (default Ghostty + install-time Kitty fallback) was more complexity
than it was worth.

- Remove ghostty.nix / nomarchy.ghostty.enable
- Kitty always installed and themed from theme-state
- Default nomarchy.terminal = kitty; SUPER+Return, doctor, calendar,
  what-changed use kitty --class=com.nomarchy.*
- Drop install-time glxinfo probe and mesa-demos on the installer
- Docs/REQUIREMENTS no longer list OpenGL 4.3 as a terminal floor

Verified: V0 flake check; option-docs; installer-safety; template HM has
kitty, no ghostty; menu/calendar emit classed kitty launches.

modules/home/rofi.nix

@@ -946,11 +946,10 @@ ${themeRows}
         exec ${cfg.terminal} -e sudo nomarchy-snapshots ;;
 
       doctor)
-        # Read-only health sheet in a floating, centered ghostty window
-        # (class matched by hyprland.nix windowrules). --gtk-single-instance
-        # =false forces a fresh window — same pattern as nomarchy-calendar.
-        # Exit code doesn't matter; the sheet itself is the product.
-        exec ghostty --class=com.nomarchy.doctor --gtk-single-instance=false \
+        # Read-only health sheet in a floating, centered kitty window
+        # (class matched by hyprland.nix windowrules). Same pattern as
+        # nomarchy-calendar. Exit code doesn't matter; the sheet is the product.
+        exec kitty --class=com.nomarchy.doctor \
           -e sh -c "nomarchy-doctor
             printf '\nEnter to close.'; read -r _" ;;
 
@@ -1045,14 +1044,14 @@ ${themeRows}
       whatchanged)
         # Plain-language last rebuild (system + desktop nvd). Toast the
         # one-liners; open a floating terminal for the full report when
-        # the user wants detail (same ghostty class pattern as Doctor).
+        # the user wants detail (same kitty class pattern as Doctor).
         if ! command -v nomarchy-what-changed >/dev/null 2>&1; then
           notify-send "What changed" "nomarchy-what-changed not on PATH (lifecycle package?)."
           exit 0
         fi
         summary=$(nomarchy-what-changed --summary 2>/dev/null || true)
         [ -n "$summary" ] && notify-send -a Nomarchy "What changed" "$summary"
-        exec ghostty --class=com.nomarchy.doctor --gtk-single-instance=false \
+        exec kitty --class=com.nomarchy.doctor \
           -e sh -c "nomarchy-what-changed
             printf '\nEnter to close.'; read -r _" ;;