Full keyboard mode, Ctrl/Alt/Super, dead keys, shift levels

- Full (iPad Pro) mode: every typing key from the keymap, number row,
  tab, caps lock, ctrl/super/alt; shifted symbol shown above and flickable
- Dead keys compose with the locale's XKB compose table
- Ctrl/Alt/Super stick like shift and turn keys into shortcuts; a tapped
  or held shift joins shortcuts and non-text keys, auto-shift and caps
  lock don't
- Auto-capitalization and caps lock only capitalize letters; the user's
  shift picks the keymap's shifted level
- Mode switch in settings keeps key size by resizing the window

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

src/settings/Settings.cpp

@@ -8,6 +8,7 @@ namespace {
 constexpr auto AutoCapitalizeKey = "typing/autoCapitalize";
 constexpr auto DoubleSpacePeriodKey = "typing/doubleSpacePeriod";
 constexpr auto VisibleSectionsKey = "layout/visibleSections";
+constexpr auto FullKeyboardKey = "layout/fullKeyboard";
 }
 
 Settings::Settings(QObject *parent)
@@ -20,6 +21,16 @@ Settings::Settings(QObject *parent)
     m_visibleSections = store.value(VisibleSectionsKey, QStringList{MainSectionId}).toStringList();
     if (m_visibleSections.isEmpty())
         m_visibleSections = {MainSectionId};
+    m_fullKeyboard = store.value(FullKeyboardKey, false).toBool();
+}
+
+void Settings::setFullKeyboard(bool full)
+{
+    if (full == m_fullKeyboard)
+        return;
+    m_fullKeyboard = full;
+    QSettings().setValue(FullKeyboardKey, full);
+    Q_EMIT fullKeyboardChanged();
 }
 
 void Settings::setSectionVisible(const QString &id, bool visible)

src/settings/Settings.h

@@ -17,6 +17,8 @@ class Settings : public QObject
     Q_PROPERTY(bool doubleSpacePeriod READ doubleSpacePeriod WRITE setDoubleSpacePeriod NOTIFY typingOptionsChanged)
     // Which key blocks are shown: "main" (the typing keys) and template section ids.
     Q_PROPERTY(QStringList visibleSections READ visibleSections NOTIFY visibleSectionsChanged)
+    // iPad Pro-style full keyboard (number row, tab, ctrl/alt/super) instead of the compact one.
+    Q_PROPERTY(bool fullKeyboard READ fullKeyboard WRITE setFullKeyboard NOTIFY fullKeyboardChanged)
 
 public:
     explicit Settings(QObject *parent = nullptr);
@@ -32,13 +34,18 @@ public:
     // Hiding the last visible section is refused: something must stay on screen.
     Q_INVOKABLE void setSectionVisible(const QString &id, bool visible);
 
+    bool fullKeyboard() const { return m_fullKeyboard; }
+    void setFullKeyboard(bool full);
+
 Q_SIGNALS:
     void typingOptionsChanged();
     void visibleSectionsChanged();
+    void fullKeyboardChanged();
 
 private:
     void setTypingOptions(const TypingOptions &options);
 
     TypingOptions m_typing;
     QStringList m_visibleSections;
+    bool m_fullKeyboard = false;
 };