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/ghostty/.config/ghostty/config.ghostty

@@ -2,7 +2,7 @@
 # Clean, simplified config for Terminess Nerd Font Mono with Catppuccin Mocha
 
 # ── Theme ──────────────────────────────────────────────────────────────────────
-theme = "Retro Legends"
+theme = noctalia
 
 # ── Font ───────────────────────────────────────────────────────────────────────
 font-family = "Terminess Nerd Font Mono"