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>

qml/Main.qml

@@ -6,7 +6,9 @@ Window {
 
     required property LayoutModel layoutModel
     required property KeyboardController controller
+    required property Settings settings
     property var placement: null // FloatingWindow, set from C++
+    property bool settingsOpen: false
 
     // Transparent room above the keyboard for long-press popups on the top row.
     readonly property real popupMargin: 90
@@ -35,16 +37,29 @@ Window {
             id: keyboard
             anchors { left: parent.left; right: parent.right; top: parent.top; bottom: handle.top }
             anchors.margins: 2
+            visible: !root.settingsOpen
             model: root.layoutModel
             controller: root.controller
         }
 
+        SettingsPanel {
+            anchors.fill: keyboard
+            visible: root.settingsOpen
+            settings: root.settings
+        }
+
         DragHandle {
             id: handle
             anchors { left: parent.left; right: parent.right; bottom: parent.bottom }
             onMoved: (dx, dy) => root.placement?.moveBy(dx, dy)
         }
 
+        SettingsButton {
+            anchors { left: parent.left; leftMargin: 8; bottom: parent.bottom }
+            checked: root.settingsOpen
+            onClicked: root.settingsOpen = !root.settingsOpen
+        }
+
         ResizeHandle {
             anchors { right: parent.right; bottom: parent.bottom }
             onResized: (dw, dh) => root.placement?.resizeBy(dw, dh)

qml/SettingsButton.qml

@@ -0,0 +1,24 @@
+import QtQuick
+
+// Gear in the grab bar; opens and closes the settings panel.
+Item {
+    id: button
+
+    property bool checked: false
+    signal clicked()
+
+    implicitWidth: 36
+    implicitHeight: 22
+
+    Text {
+        anchors.centerIn: parent
+        text: button.checked ? "⌨" : "⚙"
+        font.pixelSize: 15
+        color: tap.pressed ? Theme.text : Theme.handle
+    }
+
+    TapHandler {
+        id: tap
+        onTapped: button.clicked()
+    }
+}

qml/SettingsPanel.qml

@@ -0,0 +1,33 @@
+import QtQuick
+import Sloposk
+
+// Replaces the keys while open. Binds straight to Settings, which persists.
+Rectangle {
+    id: panel
+
+    required property Settings settings
+
+    color: Theme.background
+    radius: Theme.windowRadius
+
+    Column {
+        anchors { fill: parent; margins: 16 }
+        spacing: 4
+
+        ToggleRow {
+            width: parent.width
+            text: qsTr("Auto-Capitalization")
+            detail: qsTr("Shift at the start of a sentence")
+            checked: panel.settings.autoCapitalize
+            onToggled: checked => panel.settings.autoCapitalize = checked
+        }
+
+        ToggleRow {
+            width: parent.width
+            text: qsTr("“.” Shortcut")
+            detail: qsTr("Double-tap space for a period and a space")
+            checked: panel.settings.doubleSpacePeriod
+            onToggled: checked => panel.settings.doubleSpacePeriod = checked
+        }
+    }
+}

qml/Theme.qml

@@ -15,6 +15,7 @@ QtObject {
     readonly property color handle: dark ? "#8e8e93" : "#7c7c80"
     readonly property color accent: dark ? "#0a84ff" : "#007aff"
     readonly property color accentText: "#ffffff"
+    readonly property color toggleOn: dark ? "#30d158" : "#34c759"
 
     readonly property real windowRadius: 14
     readonly property real keyRadius: 6

qml/ToggleRow.qml

@@ -0,0 +1,57 @@
+import QtQuick
+
+// A labelled on/off switch in the iOS style.
+Item {
+    id: row
+
+    required property string text
+    property string detail: ""
+    property bool checked: false
+    signal toggled(bool checked)
+
+    implicitHeight: 52
+
+    Column {
+        anchors { left: parent.left; right: track.left; rightMargin: 12; verticalCenter: parent.verticalCenter }
+        spacing: 2
+
+        Text {
+            width: parent.width
+            text: row.text
+            color: Theme.text
+            font.pixelSize: 16
+            elide: Text.ElideRight
+        }
+        Text {
+            width: parent.width
+            visible: text !== ""
+            text: row.detail
+            color: Theme.secondaryText
+            font.pixelSize: 12
+            elide: Text.ElideRight
+        }
+    }
+
+    Rectangle {
+        id: track
+        anchors { right: parent.right; verticalCenter: parent.verticalCenter }
+        width: 50
+        height: 30
+        radius: height / 2
+        color: row.checked ? Theme.toggleOn : Theme.functionKey
+
+        Rectangle {
+            x: row.checked ? parent.width - width - 2 : 2
+            anchors.verticalCenter: parent.verticalCenter
+            width: parent.height - 4
+            height: width
+            radius: width / 2
+            color: "#ffffff"
+            Behavior on x { NumberAnimation { duration: 120 } }
+        }
+    }
+
+    TapHandler {
+        onTapped: row.toggled(!row.checked)
+    }
+}