feat(web): restore authenticated desktop home layout with modern section cards

- Add body content sections (HeroSection, NetworkStats, TrustScoreCalculator, ChainSpecs, RewardDistribution) after section grid
- Update section cards with distinct gradient header colors per category (Finance/green, Governance/purple, Social/blue, Education/orange)
- Fix bottom tab bar to be full-width (removed max-w-md mx-auto)
- Adjust role/score cards background to bg-gray-800/70 for contrast against main bg
- Add bodyOnly prop to LandingPageDesktop (non-breaking, unused)

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

web/src/components/landing/LandingPageDesktop.tsx

@@ -315,7 +315,7 @@ const PalletItem: React.FC<{
 
 // ─── Main component ───────────────────────────────────────────────────────────
 
-const LandingPageDesktop: React.FC = () => {
+const LandingPageDesktop: React.FC<{ bodyOnly?: boolean }> = ({ bodyOnly = false }) => {
   const navigate = useNavigate();
   const { t } = useTranslation();
   const { api, assetHubApi, peopleApi, isApiReady, isAssetHubReady, isPeopleReady, selectedAccount, disconnectWallet, connectWallet } = usePezkuwi();