feat: consolidate env config and add deployment files

- Add debug_font_path, demo_docs_dir, e2e_api_base_url to config.py
- Fix hardcoded paths in pp_structure_debug.py, create_demo_images.py
- Fix hardcoded paths in test files
- Update .env.example with new configuration options
- Update .gitignore to exclude AI development files (.claude/, openspec/, AGENTS.md, CLAUDE.md)
- Add production startup script (start-prod.sh)
- Add README.md with project documentation
- Add 1panel Docker deployment files (docker-compose.yml, Dockerfiles, nginx.conf)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/app/main.py

@@ -530,7 +530,7 @@ if __name__ == "__main__":
 
     uvicorn.run(
         "app.main:app",
-        host="0.0.0.0",
+        host=settings.backend_host,
         port=settings.backend_port,
         reload=True,
         log_level=settings.log_level.lower(),