feat: revamp dashboard, trades, and add landing/legal pages

- Major UI updates across dashboard, analytics, posts, trades, settings
- New landing page, robots/sitemap, contact/privacy/terms pages
- Updated globals.css with extensive styling and new landing.css
- Refactor signedRequest, realtime data hook, and dashboard store

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

.env.local.example

@@ -0,0 +1,11 @@
+# Copy to .env.local and fill in your values.
+
+# Backend REST API base URL (no trailing slash)
+# Dev:        http://localhost:8000
+# Production: https://api.yourdomain.com
+NEXT_PUBLIC_API_URL=https://api.yourdomain.com
+
+# Backend WebSocket base URL
+# Dev:        ws://localhost:8000
+# Production: wss://api.yourdomain.com
+NEXT_PUBLIC_WS_URL=wss://api.yourdomain.com