Add sites/recipe package with ExtractRecipe() that works on any recipe
URL. Parses JSON-LD structured data (@type: Recipe) first, with DOM
fallback. Handles @graph containers, arrays, HowToStep objects, ISO
8601 durations, and various author/yield/image formats.
Closes#29
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
