feat: allow initial admin setup from landing page

public/landing.html

@@ -31,6 +31,13 @@
               minlength="12"
               name="password"
               autocomplete="current-password" /></label
+          ><label
+            >Initial admin setup token (first account only)
+            <input
+              class="field-input"
+              type="password"
+              name="setupToken"
+              autocomplete="off" /></label
           ><button class="primary-btn" type="submit">Log in</button
           ><button class="ghost-btn" type="button" id="signup">
             Create account