Fix multi-monitor workspace routing regression, add laptop auto-detect

- Restore desktop DP-3=primary/DP-2=secondary workspace mapping that
  broke when workspace routing switched from name-matching to raw
  geometric ordering.
- Extract shared laptop/desktop detection + output ranking into
  lib-outputs.sh (battery presence selects the profile automatically),
  sourced by both select-workspace.sh and the new apply-outputs.sh, so
  keybind routing and monitor placement can never disagree.
- Add apply-outputs.sh: on the laptop, automatically positions whatever
  external display is plugged in (and re-runs on hotplug via swaymsg
  -t subscribe), making it primary. No-op on the desktop, which keeps
  its static fixed-arrangement config.

config/sway/scripts/lib-outputs.sh

@@ -0,0 +1,55 @@
+# Shared helpers for arranging outputs and routing workspaces across both
+# machines: the laptop (whatever external display happens to be plugged
+# in, if any) and the desktop (a fixed DP-3/DP-2 pair). Sourced by
+# apply-outputs.sh and select-workspace.sh so both always agree on which
+# output is "primary" and in what order the rest follow.
+
+is_laptop() {
+  local supply
+  for supply in /sys/class/power_supply/*/; do
+    [[ -r "${supply}type" ]] || continue
+    [[ "$(<"${supply}type")" == Battery ]] && return 0
+  done
+  return 1
+}
+
+is_internal_panel() {
+  case "$1" in
+    eDP-*|LVDS-*|DSI-*) return 0 ;;
+    *) return 1 ;;
+  esac
+}
+
+# Prints the names of currently active outputs, one per line, ordered
+# primary-first:
+#   - laptop:  any external display(s), in the order sway reports them,
+#              then the internal panel last (so a docked external is
+#              always primary; undocked, the panel is the only entry).
+#   - desktop: DP-3, then DP-2, then anything else alphabetically as a
+#              fallback for an unexpected output.
+output_order() {
+  local outputs_json name
+  outputs_json=$(swaymsg -t get_outputs -r)
+  mapfile -t active < <(jq -r '.[] | select(.active) | .name' <<<"$outputs_json")
+
+  local ordered=()
+  if is_laptop; then
+    local externals=() internals=()
+    for name in "${active[@]}"; do
+      if is_internal_panel "$name"; then internals+=("$name"); else externals+=("$name"); fi
+    done
+    ordered=("${externals[@]}" "${internals[@]}")
+  else
+    local preferred=(DP-3 DP-2) p seen
+    for p in "${preferred[@]}"; do
+      for name in "${active[@]}"; do [[ "$name" == "$p" ]] && ordered+=("$name"); done
+    done
+    for name in "${active[@]}"; do
+      seen=false
+      local o
+      for o in "${ordered[@]}"; do [[ "$o" == "$name" ]] && seen=true; done
+      "$seen" || ordered+=("$name")
+    done
+  fi
+  printf '%s\n' "${ordered[@]}"
+}