feat(admin): add status page link to dashboard header

Add a "Status" link in the admin header pointing to the public status page
(/), mirroring the existing "Go to admin" link on that page. Add a gap to
.header-actions so the new link and Logout button are spaced apart.

Co-Authored-By: Claude Opus 4.7 <[email protected]>

src/routes/admin.tsx

@@ -377,6 +377,9 @@ app.get("/", async (c) => {
             <p>Manage your email newsletter feeds</p>
           </div>
           <div class="header-actions">
+            <a href="/" class="button button-secondary">
+              Status
+            </a>
             <a href="/admin/logout" class="button button-logout">
               Logout
             </a>