Optimize OG images and add calculator usage analytics

OG Image Optimization:
- Convert all OG images from PNG to WebP format
- Reduced total size from 7.3MB to ~1MB (86% reduction)
- Updated generate-og-images.mjs to use sharp for WebP conversion
- Updated CalculatorLayout.astro and BaseLayout.astro to reference .webp

Calculator Analytics:
- Added useCalculatorTracking hook for analytics
- Added tracking to 92 calculator components
- Tracks calculator_used event with calculator name
- Uses existing window.trackCalculatorUse from Analytics.astro

Co-Authored-By: Claude Opus 4.5 <[email protected]>

Author: kitfunso