Release v0.1.3 - Static File Serving & Bug Fixes

New Features:
• Static file serving middleware with caching, security and directory browsing
• Content-type detection, If-Modified-Since support, directory traversal prevention

Bug Fixes:
• Fixed wildcard routes with trailing slash
• Fixed group prefix normalization
• Fixed Stream() nil reader panic
• Fixed timeout middleware race condition
• Fixed XSS vulnerability in directory listing

Testing:
• Added 75 comprehensive tests (325 total, 100% passing)
• Stress tests for 1000+ concurrent requests
• Integration tests for real-world workflows

See CHANGELOG.md for full details.