Noctalia theme migration: Niri IPC, GTK palette, alacritty import

- Switch Niri keybinds from qs-wrapped IPC calls to direct 'noctalia msg'
- Add noctalia.kdl include to niri config
- Replace alacritty theme with import of noctalia.toml
- Ghostty: Retro Legends → noctalia theme
- GTK3/4: accent palette shift from lavender (#bfc2ff) to purple (#b267e4)
- systemd swayidle-lock.service updated

dotfiles/alacritty/.config/alacritty/alacritty.toml

@@ -1,4 +1,5 @@
 [general]
+import = ["~/.config/alacritty/themes/noctalia.toml"]
 working_directory = "None"
 live_config_reload = true