feat(macos): Alacritty follows system light/dark appearance

New setup — due for review after you run darwin-rebuild switch and
live with it for a few days. See CLAUDE.md (Alacritty) and
assets/alacritty/README.md.

- HM: import active-colors.toml + Catppuccin latte/mocha fragments
- nix-darwin: launchd.user.agents.alacritty-system-theme + PATH helper
- fish: background sync on Darwin; theme.sh no longer rebuilds for Alacritty
- Remove switch-alacritty-theme.sh (sed + darwin-rebuild per toggle)

Made-with: Cursor

scripts/setup-simple-theme-sync.sh

@@ -1,27 +1,9 @@
 #!/bin/bash
-
-# Simple setup for Alacritty theme synchronization
-# This creates the theme file and rebuilds the Nix configuration
-
+# One-shot sync of Alacritty palette + nvim marker from current macOS appearance.
 set -e
-
-# Get the directory where this script is located
 SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
-
-echo "Setting up simple Alacritty theme synchronization..."
-
-# Run the theme sync script to create the initial theme file
-echo "Detecting current system theme..."
-"$SCRIPT_DIR/sync-alacritty-theme.sh"
-
+echo "Syncing from system appearance..."
+"$SCRIPT_DIR/alacritty-sync-system-theme.sh"
 echo ""
-echo "Setup complete!"
-echo ""
-echo "To apply the theme to Alacritty, run:"
-echo "  cd nixos && sudo darwin-rebuild switch --flake .#Daniel-Macbook-Air"
-echo ""
-echo "To sync themes when your system theme changes:"
-echo "  $SCRIPT_DIR/sync-alacritty-theme.sh && cd nixos && sudo darwin-rebuild switch --flake .#Daniel-Macbook-Air"
-echo ""
-echo "For automatic theme switching, you can set up a LaunchAgent or"
-echo "run the sync script manually when needed."
+echo "Done. Alacritty reloads colors automatically if live_config_reload is enabled."
+echo "A LaunchAgent (nix-darwin: launchd.user.agents.alacritty-system-theme) runs this every 30s."