feat(menu): hyprpicker color picker — Tools › row + SUPER+CTRL+P (item 13 done)

The last niceties slice: pick a pixel's color into the clipboard.
hyprpicker joins grim/slurp in systemPackages; a new nomarchy-menu
`colorpicker` mode captures its output, wl-copies it, and toasts the
hex (Esc = silent cancel). Tools › row self-gates on hyprpicker being
present; SUPER+CTRL+P added in keybinds.nix, so the Hyprland bind and
the SUPER+? cheatsheet row come from the one source. Item 13 complete
and deleted from BACKLOG.

Verified: V0 (flake check); V1 — template-home and template-system
build; rendered nomarchy-menu passes bash -n and contains the mode +
gated row; cheatsheet has the SUPER+CTRL+P row; hyprland.conf has the
bind; the system toplevel ships sw/bin/hyprpicker. Remains: V3 — real
loupe → click → wl-paste round-trip in a session (HARDWARE-QUEUE).

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

modules/nixos/default.nix

@@ -367,6 +367,7 @@ in
       wl-clipboard
       grim
       slurp
+      hyprpicker
     ] ++ lib.optional (cfg.snapper.enable && (config.fileSystems."/".fsType or "") == "btrfs")
       # Snapshot, then rebuild — rollback material for system changes
       # (theme changes don't need it; HM generations already roll back).