feat: add DisplaySettingsLayout with language and appearance settings

- Add language selection dropdown (Deutsch, English, Français, etc.)
- Add dark mode toggle switch
- Add theme color selection (Blue, Orange, Pink, Purple, Green)
- Enable DisplaySettingsLayout in SettingsPage menu
- Add German and English translations for all new UI strings

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Linphone/data/languages/de.ts

@@ -7838,4 +7838,52 @@ Pour les activer dans un projet commercial, merci de nous contacter.</source>
         <translation>Ok</translation>
     </message>
 </context>
+<context>
+    <name>DisplaySettingsLayout</name>
+    <message>
+        <source>settings_display_language_title</source>
+        <extracomment>Language</extracomment>
+        <translation>Sprache</translation>
+    </message>
+    <message>
+        <source>settings_display_appearance_title</source>
+        <extracomment>Appearance</extracomment>
+        <translation>Erscheinungsbild</translation>
+    </message>
+    <message>
+        <source>settings_display_language_select</source>
+        <extracomment>Language</extracomment>
+        <translation>Sprache</translation>
+    </message>
+    <message>
+        <source>settings_display_language_subtitle</source>
+        <extracomment>Select your preferred language</extracomment>
+        <translation>Wählen Sie Ihre bevorzugte Sprache</translation>
+    </message>
+    <message>
+        <source>settings_display_language_restart_hint</source>
+        <extracomment>Restart required for language change</extracomment>
+        <translation>Neustart erforderlich für Sprachwechsel</translation>
+    </message>
+    <message>
+        <source>settings_display_dark_mode_title</source>
+        <extracomment>Dark mode</extracomment>
+        <translation>Dunkelmodus</translation>
+    </message>
+    <message>
+        <source>settings_display_dark_mode_subtitle</source>
+        <extracomment>Enable dark mode for the interface</extracomment>
+        <translation>Dunkelmodus für die Oberfläche aktivieren</translation>
+    </message>
+    <message>
+        <source>settings_display_theme_color_title</source>
+        <extracomment>Theme color</extracomment>
+        <translation>Farbschema</translation>
+    </message>
+    <message>
+        <source>settings_display_theme_color_subtitle</source>
+        <extracomment>Choose the main color theme</extracomment>
+        <translation>Wählen Sie das Hauptfarbschema</translation>
+    </message>
+</context>
 </TS>

Linphone/data/languages/en.ts

@@ -7737,4 +7737,52 @@ To enable them in a commercial project, please contact us.</translation>
         <translation>Ok</translation>
     </message>
 </context>
+<context>
+    <name>DisplaySettingsLayout</name>
+    <message>
+        <source>settings_display_language_title</source>
+        <extracomment>Language</extracomment>
+        <translation>Language</translation>
+    </message>
+    <message>
+        <source>settings_display_appearance_title</source>
+        <extracomment>Appearance</extracomment>
+        <translation>Appearance</translation>
+    </message>
+    <message>
+        <source>settings_display_language_select</source>
+        <extracomment>Language</extracomment>
+        <translation>Language</translation>
+    </message>
+    <message>
+        <source>settings_display_language_subtitle</source>
+        <extracomment>Select your preferred language</extracomment>
+        <translation>Select your preferred language</translation>
+    </message>
+    <message>
+        <source>settings_display_language_restart_hint</source>
+        <extracomment>Restart required for language change</extracomment>
+        <translation>Restart required for language change</translation>
+    </message>
+    <message>
+        <source>settings_display_dark_mode_title</source>
+        <extracomment>Dark mode</extracomment>
+        <translation>Dark mode</translation>
+    </message>
+    <message>
+        <source>settings_display_dark_mode_subtitle</source>
+        <extracomment>Enable dark mode for the interface</extracomment>
+        <translation>Enable dark mode for the interface</translation>
+    </message>
+    <message>
+        <source>settings_display_theme_color_title</source>
+        <extracomment>Theme color</extracomment>
+        <translation>Theme color</translation>
+    </message>
+    <message>
+        <source>settings_display_theme_color_subtitle</source>
+        <extracomment>Choose the main color theme</extracomment>
+        <translation>Choose the main color theme</translation>
+    </message>
+</context>
 </TS>

Linphone/view/CMakeLists.txt

@@ -152,6 +152,7 @@ list(APPEND _LINPHONEAPP_QML_FILES
 	view/Page/Layout/Settings/CallSettingsLayout.qml
 	view/Page/Layout/Settings/CallForwardSettingsLayout.qml
 	view/Page/Layout/Settings/ContactsSettingsLayout.qml
+	view/Page/Layout/Settings/DisplaySettingsLayout.qml
 	view/Page/Layout/Settings/MeetingsSettingsLayout.qml
 	view/Page/Layout/Settings/ContactsSettingsProviderLayout.qml
 	view/Page/Layout/Settings/DebugSettingsLayout.qml

Linphone/view/Page/Form/Settings/SettingsPage.qml

@@ -22,7 +22,7 @@ AbstractSettingsMenu {
         //: "Réunions"
         {title: qsTr("settings_meetings_title"), layout: "MeetingsSettingsLayout", visible: !SettingsCpp.disableMeetingsFeature},
         //: "Affichage"
-        //{title: qsTr("settings_user_interface_title"), layout: "DisplaySettingsLayout"},
+        {title: qsTr("settings_user_interface_title"), layout: "DisplaySettingsLayout"},
         //: "Security"
         // {title: qsTr("settings_security_title"), layout: "SecuritySettingsLayout"},
         //: "Réseau"

Linphone/view/Page/Layout/Settings/DisplaySettingsLayout.qml

@@ -0,0 +1,116 @@
+
+import QtQuick
+import QtQuick.Layouts
+import QtQuick.Controls.Basic as Control
+import Linphone
+import SettingsCpp 1.0
+import UtilsCpp
+import 'qrc:/qt/qml/Linphone/view/Style/buttonStyle.js' as ButtonStyle
+import "qrc:/qt/qml/Linphone/view/Control/Tool/Helper/utils.js" as Utils
+
+AbstractSettingsLayout {
+	id: mainItem
+	width: parent?.width
+	contentModel: [
+		{
+			//: Language
+			title: qsTr("settings_display_language_title"),
+			subTitle: "",
+			contentComponent: languageComponent
+		},
+		{
+			//: Appearance
+			title: qsTr("settings_display_appearance_title"),
+			subTitle: "",
+			contentComponent: appearanceComponent
+		}
+	]
+
+	onSave: {
+		SettingsCpp.save()
+	}
+	onUndo: SettingsCpp.undo()
+
+	// Language settings
+	////////////////////
+
+	Component {
+		id: languageComponent
+		ColumnLayout {
+			spacing: Utils.getSizeWithScreenRatio(20)
+
+			ComboSetting {
+				Layout.fillWidth: true
+				//: Language
+				titleText: qsTr("settings_display_language_select")
+				//: Select your preferred language
+				subTitleText: qsTr("settings_display_language_subtitle")
+				propertyName: "configLocale"
+				propertyOwner: SettingsCpp
+				model: [
+					{text: "English", value: "en"},
+					{text: "Deutsch", value: "de"},
+					{text: "Francais", value: "fr"},
+					{text: "Espanol", value: "es"},
+					{text: "Portugues", value: "pt"},
+					{text: "Italiano", value: "it"},
+					{text: "Nederlands", value: "nl"},
+					{text: "Polski", value: "pl"},
+					{text: "Cesky", value: "cs"},
+					{text: "Slovensky", value: "sk"},
+					{text: "Magyar", value: "hu"},
+					{text: "Suomi", value: "fi"},
+					{text: "Russkiy", value: "ru"},
+					{text: "Ukrayinska", value: "uk"},
+					{text: "Zhongwen", value: "zh_Hans"}
+				]
+			}
+
+			Text {
+				Layout.fillWidth: true
+				//: Restart required for language change
+				text: qsTr("settings_display_language_restart_hint")
+				color: DefaultStyle.main2_500main
+				font.pixelSize: Typography.p2.pixelSize
+				wrapMode: Text.WordWrap
+			}
+		}
+	}
+
+	// Appearance settings
+	//////////////////////
+
+	Component {
+		id: appearanceComponent
+		ColumnLayout {
+			spacing: Utils.getSizeWithScreenRatio(20)
+
+			SwitchSetting {
+				Layout.fillWidth: true
+				//: Dark mode
+				titleText: qsTr("settings_display_dark_mode_title")
+				//: Enable dark mode for the interface
+				subTitleText: qsTr("settings_display_dark_mode_subtitle")
+				propertyName: "darkModeAllowed"
+				propertyOwner: SettingsCpp
+			}
+
+			ComboSetting {
+				Layout.fillWidth: true
+				//: Theme color
+				titleText: qsTr("settings_display_theme_color_title")
+				//: Choose the main color theme
+				subTitleText: qsTr("settings_display_theme_color_subtitle")
+				propertyName: "themeMainColor"
+				propertyOwner: SettingsCpp
+				model: [
+					{text: "Green", value: "green"},
+					{text: "Blue", value: "blue"},
+					{text: "Orange", value: "orange"},
+					{text: "Red", value: "red"},
+					{text: "Purple", value: "purple"}
+				]
+			}
+		}
+	}
+}