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/SsrErrorsWidget.php

@@ -33,7 +33,8 @@ final class SsrErrorsWidget implements WidgetInterface, AdditionalCssInterface
         if ($latest === null) {
             return $h::wrap('<p class="vcw-dim">No /__stats samples yet. They arrive with the next '
                 . '<code>vitec:ssr-health</code> cron run (every 5 minutes) once the node release '
-                . 'provides <code>/__stats</code>.</p>');
+                . 'provides <code>/__stats</code>.</p>', 'Cache hit rate and error counters of the SSR node, '
+                . 'filled by the health cron every 5 minutes.', 'errors');
         }
 
         $hit = (int)$latest['stat_hit'];
@@ -76,7 +77,11 @@ final class SsrErrorsWidget implements WidgetInterface, AdditionalCssInterface
             . '</div>';
         $html .= '<p class="vcw-note">Totals count since the node last started; a deploy resets them. '
             . 'Error details: <code>journalctl -u vitec-ssr</code> on the VPS.</p>';
-        return $h::wrap($html);
+        return $h::wrap($html, 'How well the SSR cache works and whether the node has problems. The ring is the '
+            . 'share of requests answered from the cache since the node last started; the bar splits them into '
+            . 'served from cache, stale and refreshed in the background, and rendered fresh. Render errors are pages '
+            . 'the node could not render, backend errors are failed requests to TYPO3. Down samples are failed '
+            . 'health checks in the last 24 hours.', 'errors');
     }
 
     public function getOptions(): array