fix(nixos): replace removed light option and harden char-count script

Restore flake checks by removing deprecated `programs.light` from sunken-ship and switching to brightnessctl guidance. Also clean up flake formatting and make the Raycast char-count script safer for empty input.

Made-with: Cursor

raycast-scripts/char-count.sh

@@ -1,4 +1,5 @@
-#!/bin/bash
+#!/usr/bin/env bash
+set -euo pipefail
 
 # Required parameters:
 # @raycast.schemaVersion 1
@@ -7,11 +8,11 @@
 
 # Optional parameters:
 # @raycast.icon 🤖
-# @raycast.argument1 { "type": "text", "placeholder": "Placeholder" }
+# @raycast.argument1 { "type": "text", "placeholder": "Text to count" }
 
 # Documentation:
 # @raycast.description counts chars in selected text
 # @raycast.author DannyDannyDanny
 # @raycast.authorURL https://raycast.com/DannyDannyDanny
 
-echo -n "$1" | wc -c
+printf '%s' "${1:-}" | wc -c | awk '{ print $1 }'