feat(planning): implement constraint-first leave planner

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

@@ -10,6 +10,17 @@
 			</div>
 		</div>
 	}
+	@if (planningOutcome()?.kind === 'InvalidInput') {
+		<p class="planning-status" role="alert">{{ tr().planning.invalidInput }}</p>
+	} @else if (planningOutcome()?.kind === 'PlanningConflict') {
+		<p class="planning-status" role="alert">{{ tr().planning.conflict }}</p>
+	} @else if (planningOutcome()?.kind === 'PlanningIncomplete') {
+		<p class="planning-status" role="status">
+			{{ hasPlannerError() ? tr().planning.error : tr().planning.incomplete }}
+		</p>
+	} @else if (planningOutcome()?.kind === 'Plan') {
+		<p class="planning-status" role="status">{{ tr().planning.complete }}</p>
+	}
 	@for (month of months; track $index) {
 		<mat-card class="card">
 			<mat-card-content>