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>

tests/TestLayouts.h

@@ -1,6 +1,6 @@
 #pragma once
 
-#include "layout/KeymapLetters.h"
+#include "layout/KeymapKeys.h"
 #include "layout/LayoutBuilder.h"
 #include "layout/LayoutLoader.h"
 
@@ -26,7 +26,7 @@ inline Layout builtinTemplate()
     return *layout;
 }
 
-inline KeymapLetters letters(const char *layout, const char *variant = nullptr)
+inline KeymapKeys keymapKeys(const char *layout, const char *variant = nullptr)
 {
     const std::unique_ptr<xkb_context, void (*)(xkb_context *)> context(
         xkb_context_new(XKB_CONTEXT_NO_ENVIRONMENT_NAMES), xkb_context_unref);
@@ -36,12 +36,12 @@ inline KeymapLetters letters(const char *layout, const char *variant = nullptr)
         xkb_keymap_new_from_names(context.get(), &names, XKB_KEYMAP_COMPILE_NO_FLAGS), xkb_keymap_unref);
     if (!keymap)
         qFatal("no XKB keymap for %s", layout);
-    return readKeymapLetters(keymap.get(), 0);
+    return readKeymapKeys(keymap.get(), 0);
 }
 
-inline Layout build(const char *layout, const char *variant = nullptr)
+inline Layout build(const char *layout, KeyboardMode mode = KeyboardMode::Compact)
 {
-    return buildLayout(builtinTemplate(), letters(layout, variant));
+    return buildLayout(builtinTemplate(), keymapKeys(layout), mode);
 }
 
 } // namespace TestLayouts