Numeric keypad spans the full keyboard height

- Sections take "fillHeight": their rows stretch over the whole key area
  instead of sitting at the bottom at the shared row height
- Rows of other blocks are unaffected; the template turns it on for the numpad

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

tests/tst_keygeometry.cpp

@@ -62,13 +62,26 @@ private Q_SLOTS:
 
     void blocksShareUnitAndSitAtTheBottom()
     {
-        const Block tall{{key(), key()}, {key(), key()}};
-        const Block shortBlock{{key()}};
+        const Block tall{{{key(), key()}, {key(), key()}}};
+        const Block shortBlock{{{key()}}};
         const auto rects = computeKeyRects({tall, shortBlock}, {400, 100}, {.padding = 0, .gap = 0, .blockGap = 100});
         // 3 units in 300 px: 100 each.
         QCOMPARE(rects[1].right(), 200.0);
         QCOMPARE(rects[4], QRectF(300, 50, 100, 50));
     }
+
+    void fillingBlockSpansTheFullHeight()
+    {
+        const Block tall{{{key()}, {key()}, {key()}, {key()}}};
+        const Block filling{{{key()}, {key()}}, true};
+        const auto rects = computeKeyRects({tall, filling}, {200, 100}, {.padding = 0, .gap = 0, .blockGap = 0});
+        QCOMPARE(rects[0].height(), 25.0);
+        QCOMPARE(rects[4], QRectF(100, 0, 100, 50));
+        QCOMPARE(rects[5], QRectF(100, 50, 100, 50));
+        // A filling block taller than the rest doesn't shrink the shared rows.
+        QCOMPARE(totalRows({tall, filling}), 4);
+        QCOMPARE(totalRows({filling}), 2);
+    }
 };
 
 QTEST_GUILESS_MAIN(TestKeyGeometry)