feat: enriched edit request system with side-by-side snapshots, calendar preloading, and admin review UI

Backend:
- Add enriched response types (EditSnapshot, EnrichedEditRequest) with original vs proposed snapshots
- Add 4 new GET endpoints for viewing edit requests (user and admin scoped)
- Remove github.com/lib/pq dependency — use native PostgreSQL array scanning
- Clean up edit requests, time blockers, and notifications on booking cancellation
- Validate exceptional closed hours on admin approve (409 Conflict)
- Notification upsert on edit request replace (no duplicate admin notifications)

Frontend:
- New user EditRequestModal with time/services/both modes and lunch protection
- New admin EditRequestModal with side-by-side diff (date/time, services, notes)
- Integrate edit requests into PendingApprovals card and notifications page
- Preload 3 months of availability to prevent calendar snap-back
- Apply lunch protection to isDateUnavailable in BookingFlow and BookingCreateModal
- Fix accessibility: card list items use <button> instead of <div>

Dev & Docs:
- Seed edit requests in local-dev-2.sh
- Update all Obsidian manuals with enriched edit request documentation
- 42 new tests (438/441 passing)

frontend/src/lib/components/admin/BookingCreateModal.svelte

@@ -197,6 +197,7 @@
 
 	// =============== Effects ===============
 	let wasOpen = false;
+	let bookingCreateInitialLoadDone = $state(false);
 
 	$effect(() => {
 		if (open && !wasOpen) {
@@ -215,16 +216,21 @@
 		}
 	});
 
+	// Preload 3 months when entering step 4 to prevent snap-back
 	$effect(() => {
-		if (open && currentStep === 4) {
-			const dateToCheck = selectedDate || placeholder;
-			fetchHoursForMonth(dateToCheck);
+		if (open && currentStep === 4 && !bookingCreateInitialLoadDone) {
+			fetchHoursRange(placeholder, 3);
+			bookingCreateInitialLoadDone = true;
 		}
 	});
 
+	// Fetch additional months when navigating beyond preloaded range
 	$effect(() => {
-		if (open && currentStep === 4 && placeholder) {
-			fetchHoursForMonth(placeholder);
+		if (open && currentStep === 4 && bookingCreateInitialLoadDone && placeholder) {
+			const monthKey = `${placeholder.year}-${String(placeholder.month).padStart(2, '0')}`;
+			if (!workingHoursCache.has(monthKey)) {
+				fetchHoursForMonth(placeholder);
+			}
 		}
 	});
 
@@ -246,6 +252,7 @@
 		availableHoursCache.clear();
 		workingHours = null;
 		availableHours = null;
+		bookingCreateInitialLoadDone = false;
 		// Clear reservation state
 		reservationId = null;
 		reservationExpiresAt = null;
@@ -304,6 +311,68 @@
 		}
 	}
 
+	async function fetchHoursRange(startDate: CalendarDate, months: number) {
+		// Calculate end month manually (CalendarDate is immutable)
+		let endYear = startDate.year;
+		let endMonth = startDate.month + months - 1;
+		while (endMonth > 12) {
+			endMonth -= 12;
+			endYear++;
+		}
+		const endMonthDate = new CalendarDate(endYear, endMonth, 1);
+		const daysInEndMonth = endMonthDate.calendar.getDaysInMonth(endMonthDate);
+
+		const startStr = startDate.toString();
+		const endStr = `${endYear}-${String(endMonth).padStart(2, '0')}-${String(daysInEndMonth).padStart(2, '0')}`;
+
+		loadingWorkingHours = true;
+		loadingAvailableHours = true;
+
+		try {
+			const [whRes, ahRes] = await Promise.all([
+				fetch(`/api/scheduling/working-hours?start=${startStr}&end=${endStr}`, {
+					headers: { Authorization: `Bearer ${authStore.currentToken}` }
+				}),
+				fetch(`/api/scheduling/available-hours?start=${startStr}&end=${endStr}`, {
+					headers: { Authorization: `Bearer ${authStore.currentToken}` }
+				})
+			]);
+
+			if (whRes.ok && ahRes.ok) {
+				const whData: WorkingHoursDay[] = await whRes.json();
+				const ahData: AvailableHoursDay[] = await ahRes.json();
+
+				const whMap: Record<string, any> = {};
+				const ahMap: Record<string, any> = {};
+
+				whData.forEach((d) => (whMap[d.date] = { isOpen: d.isOpen, startTime: d.startTime, endTime: d.endTime }));
+				ahData.forEach((d) => (ahMap[d.date] = { isOpen: d.isOpen, slots: d.slots }));
+
+				// Cache by month key
+				for (let i = 0; i < months; i++) {
+					let mYear = startDate.year;
+					let mMonth = startDate.month + i;
+					while (mMonth > 12) {
+						mMonth -= 12;
+						mYear++;
+					}
+					const key = `${mYear}-${String(mMonth).padStart(2, '0')}`;
+					workingHoursCache.set(key, whMap);
+					availableHoursCache.set(key, ahMap);
+				}
+
+				workingHours = whMap;
+				availableHours = ahMap;
+			}
+		} catch (err) {
+			console.error('Failed to fetch hours', err);
+			toast.error('Failed to load availability');
+		} finally {
+			loadingWorkingHours = false;
+			loadingAvailableHours = false;
+		}
+	}
+
 	async function fetchHoursForMonth(date: CalendarDate) {
 		const monthKey = `${date.year}-${String(date.month).padStart(2, '0')}`;
 
@@ -712,12 +781,32 @@
 		if (!workingHours) return true;
 
 		const dateStr = date.toString();
-		if (!workingHours[dateStr]?.isOpen) return true;
+		const dayHours = workingHours[dateStr];
+		if (!dayHours?.isOpen) return true;
 
 		if (selectedServices.length > 0) {
 			const duration = getTotalDuration();
 			const slots = generateAvailableTimeSlots(duration, date);
-			return slots.length === 0;
+			if (slots.length === 0) return true;
+
+			const dayAvailableHours = availableHours?.[dateStr];
+			if (dayAvailableHours?.slots) {
+				const existingBookings = extractBookedSlots(
+					dayHours.startTime,
+					dayHours.endTime,
+					dayAvailableHours.slots
+				);
+				const lunchProtection = getLunchProtectionForSlots(
+					dayHours.startTime,
+					dayHours.endTime,
+					existingBookings,
+					duration,
+					15,
+					true
+				);
+				const validSlots = slots.filter((t) => !lunchProtection.get(t)?.isBlocked);
+				if (validSlots.length === 0) return true;
+			}
 		}
 
 		return false;
@@ -1244,9 +1333,10 @@
 										selectedDate = newDate;
 										selectedTime = null;
 									}}
-									onPlaceholderChange={(newPlaceholder) => {
-										placeholder = newPlaceholder;
-									}}
+								onPlaceholderChange={(newPlaceholder) => {
+									placeholder = newPlaceholder;
+									fetchHoursForMonth(newPlaceholder);
+								}}
 								/>
 							</div>
 						{/if}