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.

.gitignore

@@ -0,0 +1,35 @@
+# Secrets — never commit tokens, keys, or credentials.
+*.token
+*.key
+*.pem
+*id_rsa*
+*id_ed25519*
+.env
+.env.*
+**/secrets/
+**/*secret*
+!config/**/secrets*.example
+
+# 1Password / auth material some machines keep alongside dotfiles.
+.config/op/
+op/*.token
+
+# Editor / tool junk.
+*.swp
+*.swo
+*~
+.DS_Store
+.netrwhist
+
+# Shell/session state that must stay per-machine.
+.zsh_history
+.zcompdump*
+.cache/
+
+# Neovim local/session artifacts.
+config/nvim/.luarc.json
+**/undodir/
+
+# Backups written by install.sh (kept under $HOME, never in-repo, but
+# ignore defensively in case one is ever created inside the checkout).
+.dotfiles-backup/