Optional PC key blocks: function row, navigation, numeric keypad

- Template sections placed above or to the right of the typing keys;
  the user picks any mix in settings, typing keys included
- keysym keys send XKB keysyms on press, optionally repeating
- Geometry lays blocks side by side with one key unit; stretch keys are
  resolved at layout time so composed blocks line up
- Toggling a block resizes the window so keys keep their size

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

src/settings/Settings.cpp

@@ -1,10 +1,13 @@
 #include "Settings.h"
 
+#include "layout/Layout.h"
+
 #include <QSettings>
 
 namespace {
 constexpr auto AutoCapitalizeKey = "typing/autoCapitalize";
 constexpr auto DoubleSpacePeriodKey = "typing/doubleSpacePeriod";
+constexpr auto VisibleSectionsKey = "layout/visibleSections";
 }
 
 Settings::Settings(QObject *parent)
@@ -14,6 +17,23 @@ Settings::Settings(QObject *parent)
     const TypingOptions defaults;
     m_typing.autoCapitalize = store.value(AutoCapitalizeKey, defaults.autoCapitalize).toBool();
     m_typing.doubleSpacePeriod = store.value(DoubleSpacePeriodKey, defaults.doubleSpacePeriod).toBool();
+    m_visibleSections = store.value(VisibleSectionsKey, QStringList{MainSectionId}).toStringList();
+    if (m_visibleSections.isEmpty())
+        m_visibleSections = {MainSectionId};
+}
+
+void Settings::setSectionVisible(const QString &id, bool visible)
+{
+    QStringList sections = m_visibleSections;
+    if (visible && !sections.contains(id))
+        sections.append(id);
+    else if (!visible)
+        sections.removeAll(id);
+    if (sections == m_visibleSections || sections.isEmpty())
+        return;
+    m_visibleSections = sections;
+    QSettings().setValue(VisibleSectionsKey, m_visibleSections);
+    Q_EMIT visibleSectionsChanged();
 }
 
 void Settings::setAutoCapitalize(bool enabled)