Only show compose button when logged in

src/app.jsx

@@ -266,6 +266,7 @@ function App() {
         </Routes>
       )}
       <div>
+        {isLoggedIn && (
           <button
             type="button"
             id="compose-button"
@@ -283,6 +284,7 @@ function App() {
           >
             <Icon icon="quill" size="xl" alt="Compose" />
           </button>
+        )}
         {isLoggedIn &&
           !snapStates.settings.shortcutsColumnsMode &&
           snapStates.settings.shortcutsViewMode !== 'multi-column' && (