feat: add unified Settings dialog (#18)

src/i18n/de.json

@@ -42,10 +42,13 @@
 	},
 	"settings": {
 		"title": "Einstellungen",
-		"description": "Einstellungen anpassen",
+		"description": "Änderungen werden automatisch gespeichert.",
 		"showWeekNumbers": "Wochennummern anzeigen",
 		"close": "Schließen",
-		"selectLanguage": "Sprache auswählen"
+		"selectLanguage": "Sprache auswählen",
+		"selectTheme": "Design",
+		"themeOptions": { "system": "System", "light": "Hell", "dark": "Dunkel" },
+		"systemAppearance": "Aktuelles Systemdesign"
 	},
 	"rules": {
 		"title": "Planungsregeln",

src/i18n/en.json

@@ -41,11 +41,14 @@
 		"any": "Any"
 	},
 	"settings": {
-		"title": "Calendar Settings",
-		"description": "Configure your calendar settings here.",
+		"title": "Settings",
+		"description": "Changes are saved automatically.",
 		"showWeekNumbers": "Show week numbers",
 		"close": "Close",
-		"selectLanguage": "Language"
+		"selectLanguage": "Language",
+		"selectTheme": "Theme",
+		"themeOptions": { "system": "System", "light": "Light", "dark": "Dark" },
+		"systemAppearance": "Current system appearance"
 	},
 	"rules": {
 		"title": "Planning rules",

src/i18n/es.json

@@ -41,11 +41,14 @@
 		"any": "Cualquier"
 	},
 	"settings": {
-		"title": "Ajustes del calendario",
-		"description": "Configure sus ajustes del calendario aquí.",
+		"title": "Ajustes",
+		"description": "Los cambios se guardan automáticamente.",
 		"showWeekNumbers": "Mostrar números de semana",
 		"close": "Cerrar",
-		"selectLanguage": "Idioma"
+		"selectLanguage": "Idioma",
+		"selectTheme": "Tema",
+		"themeOptions": { "system": "Sistema", "light": "Claro", "dark": "Oscuro" },
+		"systemAppearance": "Apariencia actual del sistema"
 	},
 	"rules": {
 		"title": "Reglas de planificación",

src/i18n/fr.json

@@ -41,11 +41,14 @@
 		"any": "N'importe"
 	},
 	"settings": {
-		"title": "Paramètres du calendrier",
-		"description": "Configurez vos paramètres de calendrier ici.",
+		"title": "Paramètres",
+		"description": "Les modifications sont enregistrées automatiquement.",
 		"showWeekNumbers": "Afficher les numéros de semaine",
 		"close": "Fermer",
-		"selectLanguage": "Langue"
+		"selectLanguage": "Langue",
+		"selectTheme": "Thème",
+		"themeOptions": { "system": "Système", "light": "Clair", "dark": "Sombre" },
+		"systemAppearance": "Apparence actuelle du système"
 	},
 	"rules": {
 		"title": "Règles de planification",