Fix double-space period, shift double-tap; settings; letters from system keymap

- Double-space replaced the space via a Backspace keysym, which clients
  apply after the commit: use delete_surrounding_text with the commit
- Tests use a shared FakeEngine that applies ops to a simulated field
- Double-tap shift locks at a sentence start; typing between taps doesn't
- Organization name set: config lives in ~/.config/sloposk/
- Settings (auto-capitalization, double-space period) with a ⚙ panel
- Letter rows come from the compositor's XKB keymap; other letters of the
  layout become long-press alternates; globe switches the system layout
  over org.kde.keyboard
- One JSON template for non-letter layers; stretch keys even out rows

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

src/CMakeLists.txt

@@ -10,15 +10,18 @@ qt_add_library(sloposk_core STATIC
     input/AlternatesPicker.h input/AlternatesPicker.cpp
     input/KeyRepeater.h input/KeyRepeater.cpp
     input/TextRules.h input/TextRules.cpp
+    input/TypingOptions.h
     input/KeyboardController.h input/KeyboardController.cpp
     input/KeyboardSurface.h input/KeyboardSurface.cpp
     layout/Layout.h
     layout/LayoutLoader.h layout/LayoutLoader.cpp
-    layout/LayoutRepository.h layout/LayoutRepository.cpp
+    layout/KeymapLetters.h layout/KeymapLetters.cpp
+    layout/LayoutBuilder.h layout/LayoutBuilder.cpp
     layout/KeyGeometry.h layout/KeyGeometry.cpp
     layout/LayoutModel.h layout/LayoutModel.cpp
     window/VisibilityController.h window/VisibilityController.cpp
     window/WindowSettings.h window/WindowSettings.cpp
+    settings/Settings.h settings/Settings.cpp
 )
 
 # QML lives in the top-level qml/ dir; alias each file so the module sees it at its root.
@@ -29,6 +32,9 @@ set(SLOPOSK_QML_FILES
     AlternatesPopup.qml
     DragHandle.qml
     ResizeHandle.qml
+    SettingsButton.qml
+    SettingsPanel.qml
+    ToggleRow.qml
     Theme.qml
 )
 list(TRANSFORM SLOPOSK_QML_FILES PREPEND ${PROJECT_SOURCE_DIR}/qml/ OUTPUT_VARIABLE sloposk_qml_paths)
@@ -55,6 +61,7 @@ target_include_directories(sloposk_core PUBLIC ${CMAKE_CURRENT_SOURCE_DIR})
 target_include_directories(sloposk_core PRIVATE
     ${CMAKE_CURRENT_SOURCE_DIR}/input
     ${CMAKE_CURRENT_SOURCE_DIR}/layout
+    ${CMAKE_CURRENT_SOURCE_DIR}/settings
 )
 target_link_libraries(sloposk_core PUBLIC Qt6::Quick PkgConfig::XKB)
 
@@ -64,9 +71,11 @@ qt_add_executable(sloposk
     main.cpp
     app/DevHooks.h app/DevHooks.cpp
     app/DBusControl.h app/DBusControl.cpp
+    app/SystemLayouts.h app/SystemLayouts.cpp
     backend/InputMethodProtocol.h
     backend/KWinInputMethod.h backend/KWinInputMethod.cpp
     backend/KWinInputContext.h backend/KWinInputContext.cpp
+    backend/WaylandKeymap.h backend/WaylandKeymap.cpp
     window/FloatingWindow.h window/FloatingWindow.cpp
 )