style: fix prefer-const and prettier formatting issues

frontend/src/lib/components/account/EditRequestModal.svelte

@@ -89,57 +89,57 @@
 	);
 	let placeholderDate = $state<CalendarDate>(minDate);
 
-	let hoursUntilAppointment = $derived(
+	const hoursUntilAppointment = $derived(
 		(new SvelteDate(booking.start_time).getTime() - new SvelteDate().getTime()) / (1000 * 60 * 60)
 	);
-	let hasPayments = $derived((booking.amount_paid ?? 0) > 0);
-	let noticePeriodBlocked = $derived(
+	const hasPayments = $derived((booking.amount_paid ?? 0) > 0);
+	const noticePeriodBlocked = $derived(
 		hasPayments ? hoursUntilAppointment < 72 : hoursUntilAppointment < 24
 	);
-	let noticePeriodWarning = $derived(
+	const noticePeriodWarning = $derived(
 		!hasPayments && hoursUntilAppointment < 24 && hoursUntilAppointment >= 0
 	);
-	let noticeBlockedMessage = $derived(
+	const noticeBlockedMessage = $derived(
 		hasPayments
 			? 'This booking has payments and is too close to the original appointment to reschedule online.'
 			: 'This booking is too close to the original appointment time to reschedule online.'
 	);
 
-	let discountTotal = $derived(
+	const discountTotal = $derived(
 		booking.discounts?.reduce((sum, d) => sum + d.discount_amount, 0) ?? 0
 	);
 
-	let bookingTotalDuration = $derived(
+	const bookingTotalDuration = $derived(
 		booking.services?.reduce(
 			(sum, s) => sum + (s.override_duration_minutes ?? s.duration_minutes ?? 0),
 			0
 		) || 0
 	);
 
-	let selectedServicesDuration = $derived(
+	const selectedServicesDuration = $derived(
 		selectedServices.reduce((sum, s) => sum + (s.duration_minutes ?? 0), 0)
 	);
 
-	let hasOverrides = $derived(
+	const hasOverrides = $derived(
 		booking?.services?.some(
 			(s) => s.override_price != null || s.override_duration_minutes != null
 		) ?? false
 	);
 
-	let slotDuration = $derived(
+	const slotDuration = $derived(
 		editMode === 'time' ? bookingTotalDuration : selectedServicesDuration
 	);
 
-	let canSubmit = $derived(
+	const canSubmit = $derived(
 		submitting === false &&
 			((editMode === 'time' && !!newDate && newTime.length >= 4) ||
 				(editMode === 'services' && selectedServices.length > 0) ||
 				(editMode === 'both-time' && !!newDate && newTime.length >= 4))
 	);
 
-	let notesChanged = $derived(notes.trim() !== originalNotes.trim());
+	const notesChanged = $derived(notes.trim() !== originalNotes.trim());
 
-	let modalTitle = $derived(() => {
+	const modalTitle = $derived(() => {
 		switch (editMode) {
 			case 'select':
 				return 'Edit/Reschedule';
@@ -193,7 +193,7 @@
 
 	function calculateEndTime(startTime: string, durationMinutes: number): string {
 		const [hours, minutes] = startTime.split(':').map(Number);
-		let total = hours * 60 + minutes + durationMinutes;
+		const total = hours * 60 + minutes + durationMinutes;
 		const h = Math.floor(total / 60);
 		const m = total % 60;
 		return `${String(h).padStart(2, '0')}:${String(m).padStart(2, '0')}`;
@@ -201,7 +201,7 @@
 
 	function calculatePreviousTime(time: string): string {
 		const [h, m] = time.split(':').map(Number);
-		let total = h * 60 + m - 15;
+		const total = h * 60 + m - 15;
 		return `${String(Math.floor(total / 60)).padStart(2, '0')}:${String(total % 60).padStart(2, '0')}`;
 	}
 
@@ -654,7 +654,7 @@
 		return Math.max(0, Math.min(nextBookingStart, workingEndMinutes) - bookingEndMinutes);
 	}
 
-	let availableAdditionalServices = $derived(() => {
+	const availableAdditionalServices = $derived(() => {
 		if (editMode !== 'services') return [];
 		const remaining = calculateRemainingTime();
 		if (remaining <= 0) return [];