Add Arch Wayland dotfiles: sway/waybar/kitty/nvim/zsh, idempotent installer

Auto-adapts sway workspace routing to however many monitors are
connected (laptop vs. desktop) instead of hardcoding output names.

config/waybar/scripts/audio-input-cycle.sh

@@ -0,0 +1,34 @@
+#!/usr/bin/env bash
+set -Eeuo pipefail
+
+source_ids=()
+current_index=-1
+
+while IFS=$'\t' read -r id is_default; do
+  [[ -n "$id" ]] || continue
+  source_ids+=("$id")
+  [[ "$is_default" == true ]] && current_index=$((${#source_ids[@]} - 1))
+done < <(
+  wpctl status -n | awk '
+    /^Audio$/ {in_audio = 1; next}
+    /^Video$/ {in_audio = 0; in_sources = 0}
+    in_audio && /Sources:/ {in_sources = 1; next}
+    /Filters:/ {in_sources = 0}
+    in_audio && in_sources && match($0, /[0-9]+\./) {
+      id = substr($0, RSTART, RLENGTH - 1)
+      print id "\t" (index($0, "*") ? "true" : "false")
+    }
+  '
+)
+
+((${#source_ids[@]} > 0)) || exit 0
+next_index=$(((current_index + 1) % ${#source_ids[@]}))
+next_source_id="${source_ids[$next_index]}"
+wpctl set-default "$next_source_id"
+
+source_name=$(
+  wpctl inspect "$next_source_id" \
+    | awk -F' = ' '/node.nick/ {gsub(/^"|"$/, "", $2); print $2; exit}'
+)
+[[ -n "$source_name" ]] || source_name="Input $next_source_id"
+notify-send -a Waybar -u low -r 9102 "Audio input changed" "$source_name"