SSR cockpit and dashboard tiles: info button with tooltip

Every tile of the module and the three SSR dashboard widgets has a round question mark button top right. Hovering it or focusing it with the keyboard shows a tooltip that explains what the tile shows. Pure CSS, anchored to the card so it never leaves the tile.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

packages/vitec/Classes/Widgets/SsrStatsWidget.php

@@ -66,7 +66,10 @@ final class SsrStatsWidget implements WidgetInterface, AdditionalCssInterface
             $html .= '<p class="vcw-dim">No samples yet: the cron job <code>vitec:ssr-health</code> fills this every 5 minutes.</p>';
         }
         $html .= '<div class="vcw-foot">' . $h::moduleLink('Charts and protocol in the cockpit') . '</div>';
-        return $h::wrap($html);
+        return $h::wrap($html, 'Availability of the SSR node over the last 24 hours, one bar per 15 minutes: '
+            . 'green ok, yellow slower than 400 ms, red down, grey no sample. Below are counts from the purge and '
+            . 'health logs: purges, full purges and failed purges, average response time, the largest cache size '
+            . 'and the browser errors reported by the frontend.', 'stats');
     }
 
     public function getOptions(): array