feat(planning): #62 #63 #64 enhance leave planner with calculation date and entitlement details

- Introduced calculationDate in various service interfaces and snapshots to track the date of planning calculations.
- Added futureEntitlement and includedEntitlement fields to the translation service and respective language files for better user feedback.
- Updated leave-planner.worker to handle calculationDate and declaredDays in requests.
- Enhanced tests to ensure proper handling of calculation dates and artifact retention during planning processes.
- Improved snapshot and explanation outputs to include calculation date for clarity in planning results.

src/app/components/calendar-year/calendar-year.ts

@@ -32,6 +32,7 @@ import { addPlanningDays } from '../../services/planning-date';
 import { isWorkingPlanningDate } from '../../services/declared-non-working-days';
 import {
 	CalendarService,
+	calendarProjectionHorizon,
 	DayType,
 	SelectedDates,
 	SelectableDayType,
@@ -481,18 +482,14 @@ export class CalendarYear {
 	protected readonly months = computed(() => {
 		const horizon = this.calendarHorizon();
 		if (!horizon) return [];
-		let first = new Date(`${horizon.start}T00:00:00`);
-		let last = new Date(`${horizon.end}T00:00:00`);
+		const plan = this.traceState() ?? this.displayedPlan();
+		const projectionHorizon =
+			!this.declarationEntry() && plan
+				? (calendarProjectionHorizon(plan) ?? horizon)
+				: horizon;
+		const first = new Date(`${projectionHorizon.start}T00:00:00`);
+		const last = new Date(`${projectionHorizon.end}T00:00:00`);
 		last.setDate(last.getDate() - 1);
-		for (const period of this.declarationEntry()
-			? []
-			: (this.displayedPlan()?.timeOffPeriods ?? [])) {
-			for (const date of period.nonWorkingDates) {
-				const contextDate = new Date(`${date}T00:00:00`);
-				if (date < horizon.start && contextDate < first) first = contextDate;
-				else if (date >= horizon.end && contextDate > last) last = contextDate;
-			}
-		}
 		const result: { monthIndex: number; year: number }[] = [];
 		const cursor = new Date(first);
 		cursor.setDate(1);
@@ -711,6 +708,7 @@ export class CalendarYear {
 				this.planningTrace.set({
 					status: 'failed',
 					initialState: {
+						calculationDate: calculation.snapshot.calculationDate,
 						horizon: calculation.snapshot.horizon,
 						...(calculation.snapshot.declaredDays
 							? { declaredDays: calculation.snapshot.declaredDays }
@@ -1306,6 +1304,7 @@ export class CalendarYear {
 			})),
 		};
 		const snapshot = (): PlanningTraceState => ({
+			calculationDate: trace.initialState.calculationDate,
 			horizon: { ...trace.initialState.horizon },
 			...(trace.initialState.declaredDays
 				? { declaredDays: trace.initialState.declaredDays }