Fix: don't squeeze the Kalender settings table into the 680px column

The reading-column max-width added for the profile panel also constrained the
wide calendar table, forcing a half-width horizontal scroll. Exempt
#settings-panel-accounts so the table uses the full width.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/css/app.css

@@ -1307,6 +1307,9 @@ a { color: var(--primary); text-decoration: none; }
 /* Constrain content to a comfortable reading column so fields don't stretch
    edge-to-edge on wide screens. */
 .settings-panel.active { display: block; max-width: 680px; }
+/* …except the Kalender panel, whose wide multi-column table needs the full
+   width (otherwise it's squeezed into a horizontal scroll). */
+#settings-panel-accounts { max-width: none; }
 
 /* Panel typography */
 .panel-title {