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/layout/LayoutBuilder.cpp

@@ -1,9 +1,7 @@
 #include "LayoutBuilder.h"
-#include "KeyGeometry.h"
 
 #include <QSet>
 
-#include <algorithm>
 
 namespace {
 
@@ -74,24 +72,6 @@ Row expandLetters(const Row &row, const KeymapLetters &letters, const QHash<QStr
     return result;
 }
 
-void stretchRows(Layer &layer)
-{
-    qreal widest = 0;
-    for (const Row &row : layer.rows)
-        widest = std::max(widest, rowUnits(row));
-
-    for (Row &row : layer.rows) {
-        const auto stretchy = std::ranges::count_if(row, &KeyDef::stretch);
-        if (stretchy == 0)
-            continue;
-        const qreal extra = (widest - rowUnits(row)) / qreal(stretchy);
-        for (KeyDef &key : row) {
-            if (key.stretch)
-                key.width += extra;
-        }
-    }
-}
-
 } // namespace
 
 Layout buildLayout(const Layout &tmpl, const KeymapLetters &letters)
@@ -104,7 +84,6 @@ Layout buildLayout(const Layout &tmpl, const KeymapLetters &letters)
     for (Layer &layer : layout.layers) {
         for (Row &row : layer.rows)
             row = expandLetters(row, letters, alternates);
-        stretchRows(layer);
     }
     return layout;
 }