Move .env into skills/ for easy install

- Added skills/_env_loader.py - shared env loader for all scripts
- Updated 17 scripts to use load_unified_env()
- Updated install-skills.sh to copy .env into skills/
- Updated README with simpler OpenClaw install instructions
- .env in skills/ is gitignored (credentials stay private)

skills/seo-multi-channel/scripts/generate_content.py

@@ -18,9 +18,9 @@ from typing import Dict, List, Optional, Any
 import yaml
 
 # Load environment variables
-from dotenv import load_dotenv
+from skills._env_loader import load_unified_env
 
-load_dotenv()
+load_unified_env()
 
 # Thai language processing
 try: