refactor(planning): remove the unused remaining-balance mirror

The summary and details already read the displayed plan's remaining
balances, so the writable mirror, its legacy conversion and the VacDay
classification/reason fields it alone populated are removed.

Refs #274

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

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

@@ -37,8 +37,6 @@ import {
 	CalendarService,
 	calendarProjectionHorizon,
 	SelectedDates,
-	SelectableDayType,
-	VacDay,
 } from '../../services/calendar-service';
 import { TranslationService } from '../../services/translation-service';
 import { UserInputService } from '../../services/user-input-service';
@@ -50,7 +48,6 @@ import {
 	LeaveType,
 	DeclaredNonWorkingDay,
 	PlanExplanation,
-	PlanOutcome,
 	PlanningCalculationContext,
 	PlanningExplanation,
 	PlanningObjective,
@@ -467,7 +464,6 @@ export class CalendarYear {
 		this.planDetailsOpen.set(false);
 		this.clearCounterfactual();
 		this.selectedDates.set(this.calendarService.getSelectedDatesForHorizon(horizon));
-		this.userInput.remainingVacationDaysSignal.set([]);
 	}
 
 	private loadArtifacts(calculation: PlanningCalculationContext): void {
@@ -517,13 +513,11 @@ export class CalendarYear {
 		if (plan) {
 			this.planningHorizon.set(plan.horizon);
 			this.selectedDates.set(this.calendarService.selectedDatesForPlan(plan));
-			this.userInput.remainingVacationDaysSignal.set(this.toLegacyBalances(plan));
 			return;
 		}
 		this.selectedDates.set(
 			this.calendarService.getSelectedDatesForHorizon(this.planningHorizon()!),
 		);
-		this.userInput.remainingVacationDaysSignal.set([]);
 	}
 
 	protected formatStatistic(value: number | null): string {
@@ -1078,16 +1072,4 @@ export class CalendarYear {
 		if (stage === 'dates') return 98;
 		return this.loadingProgress();
 	}
-
-	private toLegacyBalances(plan: PlanOutcome): VacDay[] {
-		return plan.remainingBalances.map((balance) => ({
-			id: balance.id,
-			type: balance.type as SelectableDayType,
-			numberOfDays: balance.quantity,
-			availableDate: new Date(`${balance.availableFrom}T00:00:00`),
-			expiryDate: new Date(`${balance.expiryDate}T00:00:00`),
-			classification: balance.classification,
-			reason: balance.reason,
-		}));
-	}
 }