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>

tests/tst_controller.cpp

@@ -1,7 +1,7 @@
-#include "engine/InputEngine.h"
+#include "FakeEngine.h"
 #include "input/KeyboardController.h"
 #include "layout/LayoutModel.h"
-#include "layout/LayoutRepository.h"
+#include "TestLayouts.h"
 
 #include <QTest>
 #include <xkbcommon/xkbcommon-keysyms.h>
@@ -10,21 +10,6 @@ using namespace Qt::StringLiterals;
 
 namespace {
 
-class FakeEngine : public InputEngine
-{
-public:
-    void commitText(const QString &text) override { output += text; }
-    void sendKeysym(quint32 keysym, Qt::KeyboardModifiers modifiers) override
-    {
-        keysyms.append(keysym);
-        lastModifiers = modifiers;
-    }
-
-    QString output;
-    QList<quint32> keysyms;
-    Qt::KeyboardModifiers lastModifiers;
-};
-
 KeyDef makeKey(KeyType type, const QString &label = {})
 {
     KeyDef k;
@@ -41,7 +26,6 @@ class TestController : public QObject
 
 private:
     FakeEngine engine;
-    LayoutRepository repo;
     LayoutModel model;
     std::unique_ptr<KeyboardController> controller;
     qint64 now = 0;
@@ -57,11 +41,8 @@ private Q_SLOTS:
     void init()
     {
         engine = {};
-        repo = {};
-        Q_INIT_RESOURCE(layouts);
-        repo.loadDirectory(u":/layouts"_s);
-        repo.finalize(u"en_US"_s);
-        controller = std::make_unique<KeyboardController>(engine, model, repo);
+        model.setLayout(TestLayouts::build("us"));
+        controller = std::make_unique<KeyboardController>(engine, model);
     }
 
     void typesLowercase()
@@ -156,11 +137,44 @@ private Q_SLOTS:
         tap(makeKey(KeyType::Character, u"a"_s));
         tap(space);
         tap(space);
-        QCOMPARE(engine.output, u"a . ");
-        QCOMPARE(engine.keysyms, QList<quint32>{XKB_KEY_BackSpace}); // removed the first space
+        QCOMPARE(engine.output, u"a. ");
+        QCOMPARE(engine.mismatchedReplacements, 0);
+        // A Backspace keysym may reach the client after the commit and eat the new space.
+        QVERIFY(engine.keysyms.isEmpty());
         QCOMPARE(controller->shiftMode(), KeyboardController::ShiftMode::Once);
     }
 
+    void doubleSpacePeriodCanBeTurnedOff()
+    {
+        controller->setOptions({.doubleSpacePeriod = false});
+        const KeyDef space = makeKey(KeyType::Space);
+        tap(makeKey(KeyType::Character, u"a"_s));
+        tap(space);
+        tap(space);
+        QCOMPARE(engine.output, u"A  ");
+    }
+
+    void autoCapitalizationCanBeTurnedOff()
+    {
+        controller->resetContext();
+        controller->setOptions({.autoCapitalize = false});
+        QCOMPARE(controller->shiftMode(), KeyboardController::ShiftMode::Off);
+        tap(makeKey(KeyType::Character, u"a"_s));
+        QCOMPARE(engine.output, u"a");
+    }
+
+    void doubleTapShiftLocksAtSentenceStart()
+    {
+        controller->resetContext(); // a field was focused
+        QCOMPARE(controller->shiftMode(), KeyboardController::ShiftMode::Once); // auto-shift
+        const KeyDef shift = makeKey(KeyType::Shift);
+        controller->keyDown(shift, 5000);
+        controller->keyUp(shift, KeyOutput::Primary, {}, 5050);
+        controller->keyDown(shift, 5200);
+        controller->keyUp(shift, KeyOutput::Primary, {}, 5250);
+        QCOMPARE(controller->shiftMode(), KeyboardController::ShiftMode::Locked);
+    }
+
     void slideTypesSymbolAndSwitchesBack()
     {
         KeyDef layer = makeKey(KeyType::LayerSwitch);
@@ -177,13 +191,12 @@ private Q_SLOTS:
         QCOMPARE(engine.keysyms, (QList<quint32>{XKB_KEY_Right, XKB_KEY_Right, XKB_KEY_Up}));
     }
 
-    void globeCyclesLayouts()
+    void globeRequestsNextLayout()
     {
-        QCOMPARE(model.layoutName(), u"English (US)");
+        int requested = 0;
+        connect(controller.get(), &KeyboardController::nextLayoutRequested, this, [&] { ++requested; });
         tap(makeKey(KeyType::Globe));
-        QCOMPARE(model.layoutName(), u"Svenska");
-        tap(makeKey(KeyType::Globe));
-        QCOMPARE(model.layoutName(), u"English (US)");
+        QCOMPARE(requested, 1);
     }
 
     void dismissEmitsSignal()