Simple web content fetching without API keys or external dependencies. Uses Python stdlib (urllib) only. Features: fetch HTML/text from URLs, basic HTML to markdown conversion, path-validated file writes (blocks system paths), URL validation (blocks localhost/internal). Security: File writes use is_safe_path() to prevent malicious writes. Perfect for content aggregation, research collection, and web scraping without API costs or dependencies.

无需API密钥或外部依赖的简单网页内容获取工具，仅使用Python标准库（urllib）。支持从URL获取HTML/文本内容，提供基本的HTML转Markdown功能，并通过路径校验确保文件写入安全（阻止系统路径访问），同时校验URL（阻止本地主机和内网地址）。文件写入使用is_safe_path()防止恶意写入，适用于无API成本和依赖的内容聚合、研究收集和网页抓取。