Add Grapes section with variety profiles, grape filter & cross-links

- New "Grapes" tab: Cabernet Sauvignon, Merlot, Pinot Noir, Syrah/Shiraz
- Range bars show each grape's typical body/tannin/acidity span
- Flavor, oak, blending-partner and region info per grape
- "Wines in this guide" chips cross-link into the Wine Finder
- New Grape filter dropdown in the Wine Finder
- Grape-characteristic questions added to the Quiz pool

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: KaylinCHCH