test(calendar): pin the clock for the Paris today marker

The test of the today marker read the wall clock, so it only exercised
the Paris/local date mismatch between 22:00 and 24:00 UTC and passed
with or without the fix the rest of the day. Pin the clock to 22:16 UTC,
already the next day in Paris, so a UTC runner fails without the fix at
any time.

Refs #301

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

src/app/services/calendar-service.spec.ts

@@ -8,6 +8,7 @@ import {
 	SelectedDates,
 } from './calendar-service';
 import { DateRange } from '@angular/material/datepicker';
+import { vi } from '../../testing/vitest-compat';
 
 describe('CalendarService', () => {
 	let service: CalendarService;
@@ -197,6 +198,8 @@ describe('CalendarService', () => {
 			service.project({ placements: [], horizon });
 		const day = (key: string) => new Date(`${key}T00:00:00`);
 
+		afterEach(() => vi.useRealTimers());
+
 		it('projects weekends, holidays and today for the default planning horizon', () => {
 			const { selections } = project({ start: '2026-01-01', end: '2027-01-01' });
 			expect(selections.dayTypes(day('2026-05-09'))).toContain(DayType.WEEKEND);
@@ -207,6 +210,15 @@ describe('CalendarService', () => {
 			);
 		});
 
+		it('marks today on the Europe/Paris date when the runtime date is still the day before', () => {
+			vi.setSystemTime(new Date('2026-10-17T22:16:00Z'));
+			const horizon = service.getDefaultPlanningHorizon();
+			expect(horizon.start).toBe('2026-10-18');
+			const { selections } = project(horizon);
+			expect(selections.getClasses(day('2026-10-18'))).toContain(DayType.TODAY);
+			expect(selections.getClasses(day('2026-10-17'))).not.toContain(DayType.TODAY);
+		});
+
 		it('lists the covered months, including partial boundary months and year changes', () => {
 			expect(project({ start: '2024-11-20', end: '2025-02-02' }).months).toEqual([
 				{ monthIndex: 10, year: 2024 },