fix: update community link to Discord server

src/App.svelte

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         <div class="button-group">
           <a href="https://signup.tophhie.social" class="call-to-action">Sign up now!</a>
           <a href="https://migrate.tophhie.social" class="call-to-action">Migrate your Bluesky account!</a>
-          <a href="https://aka.tophhie.cloud/socialcommunitysignup" class="call-to-action">Join the Tophhie Social Community!</a>
+          <a href="https://discord.gg/YD8sF8JsCJ" class="call-to-action">Join the Tophhie Cloud Discord server!</a>
           <a href="https://status.tophhie.social" class="call-to-action">Server Status</a>
         </div>
         <div id="accountsList">