feat: WCAG AA accessibility, code splitting, responsive ads layout

- Add React.lazy code splitting for all 15 tool pages
- Fix WCAG AA contrast issues (304 text color fixes)
- Add ARIA labels and aria-expanded to navigation buttons
- Add aria-live for error announcements in tools
- Implement responsive ad layout:
  - Desktop (≥1280px): Right sidebar with 3 ad units
  - Tablet (1024-1279px): Bottom section with 3 horizontal units
  - Mobile (<1024px): Fixed bottom banner
- Add TabletAdSection component for tablet ad placement
- Integrate Onidel affiliate partnership
- Update all Adsterra domains to solutionbiologyisle.com
- Add release notes for 2026-02-18 updates

src/components/NavigationConfirmModal.js

@@ -73,7 +73,7 @@ const NavigationConfirmModal = ({ isOpen, onConfirm, onCancel, targetPath, hasDa
               <p className="text-sm font-medium text-gray-700 dark:text-gray-300 mb-2">
                 You currently have:
               </p>
-              <ul className="text-sm text-gray-600 dark:text-gray-400 space-y-1">
+              <ul className="text-sm text-gray-600 dark:text-gray-600 space-y-1">
                 {dataSummary.map((item, index) => (
                   <li key={index} className="flex items-center">
                     <span className="w-1.5 h-1.5 bg-amber-500 rounded-full mr-2 flex-shrink-0"></span>