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>

app/robots.ts

@@ -0,0 +1,22 @@
+import type { MetadataRoute } from 'next'
+
+const siteUrl = process.env.NEXT_PUBLIC_SITE_URL
+
+export default function robots(): MetadataRoute.Robots {
+  if (!siteUrl) {
+    return {
+      rules: {
+        userAgent: '*',
+        allow: '/',
+      },
+    }
+  }
+
+  return {
+    rules: {
+      userAgent: '*',
+      allow: '/',
+    },
+    sitemap: `${siteUrl}/sitemap.xml`,
+  }
+}