feat: Add 19 free QR code tools with SEO optimization

- Added PayPal, Zoom, Teams QR generators
- Added lazy loading for html-to-image (performance)
- Created 19 OG images for social sharing
- Added robots.txt and updated sitemap
- Fixed mobile navigation with accordion menu
- Added 7 color options per generator
- Fixed crypto QR with universal/wallet mode toggle
- Hero QR codes all point to qrmaster.net

src/i18n/en.json

@@ -9,7 +9,8 @@
     "create_qr": "Create QR",
     "bulk_creation": "Bulk Creation",
     "analytics": "Analytics",
-    "settings": "Settings"
+    "settings": "Settings",
+    "cta": "Get Started Free"
   },
   "hero": {
     "badge": "Free QR Code Generator",