feat(blankpad): desk.sh profile switcher, hotplug autoswitch daemon, keybinds doc generator + bats suite

- desk.sh: list/current/switch/cycle/match/capture over cfg/desk-*.kdl
  profiles; apply = relink display.kdl, niri validate (rollback on fail),
  load-config-file, noctalia notification; match scores // requires: lines
  (EDID long names) against live niri msg outputs
- desk-autoswitch.sh: watch niri msg --json event-stream for
  OutputsChanged, debounced desk.sh match --apply, reconnect loop
- blankpad-desk-autoswitch.service: ConditionHost=blankpad user unit
- gen-keybinds.sh: keybinds.kdl -> markdown cheat sheet (sections from
  // --- headers, hotkey-overlay-title preferred over action)
- tests/: 27 bats cases, all green (desk 16, gen-keybinds 6,
  niri-config 5 incl. real niri validate on the assembled tree with
  each desk profile active)

dotfiles/zz-blankpad/.config/systemd/user/blankpad-desk-autoswitch.service

@@ -0,0 +1,19 @@
+[Unit]
+Description=Desk Profile Auto-Switch for Blankpad
+After=graphical-session.target
+ConditionHost=blankpad
+
+[Service]
+Type=simple
+User=%u
+Group=%u
+ExecStart=/usr/bin/env bash %h/.omp/scripts/desk-autoswitch.sh watch
+Restart=on-failure
+RestartSec=5
+StandardOutput=journal
+StandardError=journal
+Environment=DESK_NIRI=/usr/bin/niri
+Environment=DESK_NOTIFY=noctalia msg notification-show
+
+[Install]
+WantedBy=default.target