feat(frontend): integrate custom services across booking flow and routes

Update BookingFlow to support custom service selection, add custom_services to booking types, and link CustomServicesManagement into admin pages. Minor updates to schedules, prices, and today routes.

Ultraworked with Sisyphus (https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

frontend/src/lib/components/booking/BookingFlow.svelte

@@ -1514,10 +1514,19 @@
 					{services}
 					selected={selectedServices}
 					loading={servicesLoading}
-					ontoggle={toggleService}
-				/>
+			ontoggle={toggleService}
+			/>
 
-				{#if selectedServices.length > 0}
+			<div class="mt-4 rounded-lg border border-dashed border-gray-300 bg-gray-50 p-4 text-center">
+				<p class="text-sm text-gray-600">
+					Need something different? Select the closest service and add a note, or contact us for a bespoke treatment.
+				</p>
+				<a href="/contact" class="mt-1 inline-block text-sm font-medium text-blue-600 hover:underline">
+					Arrange a custom booking →
+				</a>
+			</div>
+
+			{#if selectedServices.length > 0}
 					<div class="rounded-lg bg-gray-50 p-4">
 						<h4 class="mb-2 font-semibold">Selected Services</h4>
 						<div class="space-y-2">

frontend/src/lib/components/today/TodayCalendar.svelte

@@ -744,7 +744,7 @@
 										{item.data.user_name}
 									</button>
 									<div class="flex flex-wrap items-center gap-x-1 text-sm text-gray-600">
-										<span class="truncate">{item.data.services.join(', ')}</span>
+										<span class="truncate">{(item.data.services ?? []).join(', ')}</span>
 										<span
 											class="shrink-0 rounded-full bg-gray-100 px-1.5 py-0.5 text-xs font-medium"
 										>