Lab: remember-me, Grafana proxy fix, builder cache dirs, branded QR alerts.

Grafana auth restore + nginx proxy_cookie_path; alert-notifier branded QR; prepare-be-builder-dirs shared ccache/gradle; bump ac-scripts for Docker DLC maintenance.

Co-authored-by: Cursor <cursoragent@cursor.com>

sim/cluster0/lab-seeds/backend/views/login.php

@@ -53,6 +53,7 @@ $loginRedirect = $loginRedirect ?? '';
     <?php endif; ?>
     <label><span data-i18n="login.username">Username</span><input name="username" autocomplete="username" required></label>
     <label><span data-i18n="login.password">Password</span><input name="password" type="password" autocomplete="current-password" required></label>
+    <label class="build-form-checks"><input type="checkbox" name="remember_me" value="1"> <span data-i18n="login.remember_me">Remember me on this device</span></label>
     <button type="submit" data-i18n="login.submit">Sign in</button>
     <p class="hint"><a href="<?= h($auth) ?>/register" data-i18n="login.register">Create account</a></p>
   </form>