buildRecipePrompt ignored req.Lang entirely and hardcoded two
English instructions in the prompt. Added targetLang resolution
using the existing langNames map (from recognition.go) and
threaded it into both "Generate N recipes in …" and "All text
fields … MUST be in …" instructions. The image_query field
remains English since it is passed to the Pexels photo API.
Fixes recommendations and menu recipes being returned in English
regardless of the Accept-Language header.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
cba50489be