Layouts, iPad-style rendering, taps, shift and layers

- JSON layouts (en-US, sv-SE inheriting number/symbol layers via base)
- LayoutModel + KeyGeometry: proportional rows, nearest-key hit testing
- KeyboardSurface: multi-pointer touch/mouse routing to the controller
- KeyboardController + ShiftState: iOS shift/caps-lock, layers, globe, dismiss
- QML view with light/dark iPad palette and drag handle
- DevHooks: SLOPOSK_AUTOTYPE, SLOPOSK_SCREENSHOT for headless checks
- Unit tests for shift, loader, geometry and controller

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

CMakeLists.txt

@@ -5,7 +5,7 @@ set(CMAKE_CXX_STANDARD 20)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
 
-find_package(Qt6 6.8 REQUIRED COMPONENTS Gui Quick Widgets WaylandClient)
+find_package(Qt6 6.8 REQUIRED COMPONENTS Gui Quick Widgets Test WaylandClient)
 find_package(LayerShellQt REQUIRED)
 find_package(PkgConfig REQUIRED)
 pkg_check_modules(XKB REQUIRED IMPORTED_TARGET xkbcommon)
@@ -14,5 +14,8 @@ pkg_get_variable(WAYLAND_PROTOCOLS_DIR wayland-protocols pkgdatadir)
 
 qt_standard_project_setup(REQUIRES 6.8)
 
+enable_testing()
+
 add_subdirectory(src)
 add_subdirectory(tools)
+add_subdirectory(tests)