docs(privacy): clarify decryption key is not stored for shared plans

For provenance purposes, this commit was AI assisted.

Author: backnotprop

apps/marketing/src/pages/privacy.astro

@@ -53,6 +53,7 @@ import Footer from '../components/Footer.astro';
         <h3>a. Shared plan data</h3>
         <p>If you use hosted sharing for larger plans, we may temporarily store an encrypted version of the shared plan so the short link can work.</p>
         <p>We do not store unencrypted shared plan contents through that flow.</p>
+        <p>We do not store the decryption key. Because the key is not stored by our hosted service, we cannot access the unencrypted contents of shared plans through this flow.</p>
 
         <h3>b. Basic infrastructure data</h3>
         <p>Our hosted services rely on infrastructure providers such as AWS, CloudFront, and Cloudflare. As a result, limited technical data such as IP addresses or request metadata may be processed by those providers as part of delivering the service.</p>