Remove PostHog analytics and update dependencies to latest minor versions

- Remove posthog-js and posthog-node dependencies
- Delete PostHogProvider component and lib/posthog.ts
- Remove PostHog configuration from environment files
- Remove PostHog rewrites from next.config.mjs
- Update all npm subdependencies to latest minor versions
- Update @types/react and @types/react-dom overrides to 19.2.9 and 19.2.3

next.config.mjs

@@ -53,25 +53,6 @@ const nextConfig = {
       },
     ];
   },
-  async rewrites() {
-    return [
-      {
-        source: '/ingest/static/:path*',
-        destination: 'https://us-assets.i.posthog.com/static/:path*',
-      },
-      {
-        source: '/ingest/:path*',
-        destination: 'https://us.i.posthog.com/:path*',
-      },
-      {
-        source: '/ingest/decide',
-        destination: 'https://us.i.posthog.com/decide',
-      },
-    ];
-  },
-  // This is required to support PostHog trailing slash API requests
-  skipTrailingSlashRedirect: true,
-
 };
 
 export default nextConfig;