feat(hyprland): launch-or-focus binds (item 17)

nomarchy.launchOrFocus (opt-in, commented template example): each
entry gives a key that FOCUSES the app's existing window
(case-insensitive class match via jq + a "(?i)" focuswindow regex) or
launches it when none is open. One shared nomarchy-focus-or-launch
script; a bind whose command was removed from the suite fires a
"not installed" toast instead of failing silently. The same entries
render into the SUPER+? cheatsheet through prettyKeys — bind and
documentation stay one source. README row added.

Verified: V0; V1 — a scratch downstream with two entries renders both
binds (default command = lowercased class; custom mods/command/desc
honored), the script passes bash -n with a usage guard, and the
cheatsheet carries both rows. Focus behaviour needs a session -> V3
(HARDWARE-QUEUE).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

templates/downstream/home.nix

@@ -34,6 +34,11 @@
   #   { name = "HDMI-A-1"; position = "auto-right"; }
   # ];                                  #   names from `hyprctl devices`
   #
+  # nomarchy.launchOrFocus = [          # SUPER+<key> focuses the app's window,
+  #   { key = "B"; class = "firefox"; } #   or launches it if none is open;
+  #   { key = "O"; class = "obsidian"; }#   rows appear in the SUPER+? cheatsheet
+  # ];                                  #   (class from `hyprctl clients`)
+  #
   # nomarchy.displayProfiles = {        # named layouts for the SAME outputs —
   #   docked = [                        #   switch: System › Display › Profiles
   #     { name = "eDP-1"; resolution = "disable"; }