feat(planner): implement cancellation for planning calculations

- Refactor leave-planner.worker.ts to support cancellation of ongoing calculations.
- Introduce `calculatePlanningAsyncInternal` for asynchronous planning calculations.
- Add cancellation handling in the worker message event.
- Update planning-date.ts with new utility functions for date manipulation.
- Extend translation-service.ts and translation files (en.json, de.json, es.json, fr.json) to include new strings related to planning horizon and cancellation.
- Create documentation for the cancellation feature in planner-cancellation.md.
- Add unit tests for cancellation functionality in leave-planner-cancellation.spec.ts and leave-planner.worker.spec.ts.

#57 #58

src/i18n/de.json

@@ -48,7 +48,14 @@
 		"selectLanguage": "Sprache auswählen",
 		"selectTheme": "Design",
 		"themeOptions": { "system": "System", "light": "Hell", "dark": "Dunkel" },
-		"systemAppearance": "Aktuelles Systemdesign"
+		"systemAppearance": "Aktuelles Systemdesign",
+		"planningHorizon": "Planungszeitraum",
+		"planningStart": "Startdatum (einschließlich)",
+		"lastPlanningDate": "Letzter Planungstag (einschließlich)",
+		"planningDatesHelp": "Wählen Sie beliebige Daten, auch vergangene. Der Kalender wird aktualisiert, wenn Sie Plan berechnen auswählen.",
+		"invalidDate": "Geben Sie zwei gültige Kalenderdaten ein.",
+		"horizonOrder": "Der letzte Planungstag muss am oder nach dem Startdatum liegen.",
+		"invalidHorizon": "Korrigieren Sie die Planungsdaten in den Einstellungen vor der Berechnung."
 	},
 	"rules": {
 		"title": "Planungsregeln",
@@ -109,6 +116,10 @@
 		"invalidInput": "Die Planungsdaten sind ungültig.",
 		"conflict": "Die Verpflichtungen können nicht gemeinsam erfüllt werden.",
 		"incomplete": "Die Berechnung wurde vor Abschluss aller Qualitätsstufen beendet.",
+		"cancel": "Abbrechen",
+		"cancelling": "Berechnung wird abgebrochen…",
+		"cancelled": "Berechnung abgebrochen",
+		"cancelledPartial": "Berechnung abgebrochen — Teilplan",
 		"error": "Bei der Planung ist ein unerwarteter Fehler aufgetreten.",
 		"complete": "Plan berechnet.",
 		"whyPlacement": "Ihre Urlaubstage verstehen",

src/i18n/en.json

@@ -48,7 +48,14 @@
 		"selectLanguage": "Language",
 		"selectTheme": "Theme",
 		"themeOptions": { "system": "System", "light": "Light", "dark": "Dark" },
-		"systemAppearance": "Current system appearance"
+		"systemAppearance": "Current system appearance",
+		"planningHorizon": "Planning horizon",
+		"planningStart": "Start date (inclusive)",
+		"lastPlanningDate": "Last planning date (inclusive)",
+		"planningDatesHelp": "Choose any dates, including past dates. Your calendar updates when you select Calculate plan.",
+		"invalidDate": "Enter two valid calendar dates.",
+		"horizonOrder": "The last planning date must be on or after the start date.",
+		"invalidHorizon": "Correct the planning dates in Settings before calculating."
 	},
 	"rules": {
 		"title": "Planning rules",
@@ -109,6 +116,10 @@
 		"invalidInput": "The planning input is invalid.",
 		"conflict": "The obligations cannot be satisfied together.",
 		"incomplete": "Calculation stopped before all quality stages completed.",
+		"cancel": "Cancel",
+		"cancelling": "Cancelling…",
+		"cancelled": "Calculation cancelled",
+		"cancelledPartial": "Calculation cancelled — partial plan",
 		"error": "The planner encountered an unexpected error.",
 		"complete": "Plan calculated.",
 		"whyPlacement": "Understand your leave days",

src/i18n/es.json

@@ -48,7 +48,14 @@
 		"selectLanguage": "Idioma",
 		"selectTheme": "Tema",
 		"themeOptions": { "system": "Sistema", "light": "Claro", "dark": "Oscuro" },
-		"systemAppearance": "Apariencia actual del sistema"
+		"systemAppearance": "Apariencia actual del sistema",
+		"planningHorizon": "Horizonte de planificación",
+		"planningStart": "Fecha de inicio (incluida)",
+		"lastPlanningDate": "Última fecha de planificación (incluida)",
+		"planningDatesHelp": "Elige cualquier fecha, incluso pasada. El calendario se actualiza al seleccionar Calcular plan.",
+		"invalidDate": "Introduce dos fechas válidas.",
+		"horizonOrder": "La última fecha de planificación debe ser igual o posterior a la fecha de inicio.",
+		"invalidHorizon": "Corrige las fechas de planificación en Ajustes antes de calcular."
 	},
 	"rules": {
 		"title": "Reglas de planificación",
@@ -109,6 +116,10 @@
 		"invalidInput": "Los datos de planificación no son válidos.",
 		"conflict": "Las obligaciones no se pueden satisfacer juntas.",
 		"incomplete": "El cálculo se detuvo antes de completar todas las etapas de calidad.",
+		"cancel": "Cancelar",
+		"cancelling": "Cancelando…",
+		"cancelled": "Cálculo cancelado",
+		"cancelledPartial": "Cálculo cancelado — plan parcial",
 		"error": "El planificador encontró un error inesperado.",
 		"complete": "Plan calculado.",
 		"whyPlacement": "Entender tus días de permiso",

src/i18n/fr.json

@@ -48,7 +48,14 @@
 		"selectLanguage": "Langue",
 		"selectTheme": "Thème",
 		"themeOptions": { "system": "Système", "light": "Clair", "dark": "Sombre" },
-		"systemAppearance": "Apparence actuelle du système"
+		"systemAppearance": "Apparence actuelle du système",
+		"planningHorizon": "Horizon de planification",
+		"planningStart": "Date de début (incluse)",
+		"lastPlanningDate": "Dernière date de planification (incluse)",
+		"planningDatesHelp": "Choisissez vos dates, même passées. Le calendrier est mis à jour lorsque vous cliquez sur Calculer le planning.",
+		"invalidDate": "Saisissez deux dates calendaires valides.",
+		"horizonOrder": "La dernière date de planification doit être égale ou postérieure à la date de début.",
+		"invalidHorizon": "Corrigez les dates de planification dans les paramètres avant de calculer."
 	},
 	"rules": {
 		"title": "Règles de planification",
@@ -109,6 +116,10 @@
 		"invalidInput": "Les données de planification sont invalides.",
 		"conflict": "Les obligations ne peuvent pas être satisfaites ensemble.",
 		"incomplete": "Le calcul s’est arrêté avant la fin des critères de qualité.",
+		"cancel": "Annuler",
+		"cancelling": "Annulation en cours…",
+		"cancelled": "Calcul annulé",
+		"cancelledPartial": "Calcul annulé — plan partiel",
 		"error": "Le planificateur a rencontré une erreur inattendue.",
 		"complete": "Plan calculé.",
 		"whyPlacement": "Comprendre vos jours de congé",