feat: PhotoPrism M0 bring-up — compose stack, web client, sidecar, migrate

Replace the legacy mule-image backend with PhotoPrism plus a thin
SvelteKit client and a Node sidecar for endpoints PhotoPrism doesn't
expose (file rename), and add a two-phase migrator (metadata via PUT,
heaps → albums) for the existing Postgres library.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

web/src/routes/duplicates/+page.svelte

@@ -0,0 +1,67 @@
+<script lang="ts">
+	import { createQuery } from '@tanstack/svelte-query';
+	import {
+		listDuplicateGroups,
+		type DuplicateGroup
+	} from '$lib/services/adapters/duplicates';
+	import { isAuthenticated } from '$lib/stores/session.svelte';
+	import {
+		setThumbnailSize,
+		THUMBNAIL_SIZE_LABELS,
+		THUMBNAIL_SIZE_PRESETS,
+		view
+	} from '$lib/stores/view.svelte';
+	import Toolbar from '$lib/components/layout/Toolbar.svelte';
+	import DuplicatesView from '$lib/components/duplicates/DuplicatesView.svelte';
+
+	// Stale-time matches mule-image's DuplicatesView (30 s) so quick
+	// toolbar bounces don't refetch the (potentially expensive) stack
+	// listing. Invalidation by mutations is explicit, not time-driven.
+	const dupesQuery = createQuery<DuplicateGroup[]>(() => ({
+		queryKey: ['duplicates'],
+		queryFn: listDuplicateGroups,
+		enabled: isAuthenticated(),
+		staleTime: 30_000
+	}));
+</script>
+
+<Toolbar>
+	<span class="rounded-md border border-border px-2 py-0.5 text-[11px] text-muted-foreground">
+		Duplicates · stacks
+	</span>
+	{#snippet trailing()}
+		<!-- Thumbnail-size control mirrors the timeline Toolbar. The view
+		     store is global, so the picked size persists across routes —
+		     when you come back to the timeline it stays where you left it. -->
+		<div
+			class="flex items-center overflow-hidden rounded border border-border"
+			role="group"
+			aria-label="Thumbnail size"
+		>
+			{#each THUMBNAIL_SIZE_PRESETS as size, i (size)}
+				<button
+					type="button"
+					class="px-1.5 py-0.5 text-[10px] font-medium hover:bg-accent"
+					class:bg-accent={view.thumbnailSize === size}
+					class:text-foreground={view.thumbnailSize === size}
+					class:text-muted-foreground={view.thumbnailSize !== size}
+					onclick={() => setThumbnailSize(size)}
+					title={`${THUMBNAIL_SIZE_LABELS[i]} · ${size}px`}
+				>
+					{THUMBNAIL_SIZE_LABELS[i]}
+				</button>
+			{/each}
+		</div>
+		<span class="text-[11px] text-muted-foreground">
+			{dupesQuery.data?.length ?? 0} group{dupesQuery.data?.length === 1 ? '' : 's'}
+		</span>
+	{/snippet}
+</Toolbar>
+
+<main class="min-h-0 flex-1 overflow-y-auto">
+	<DuplicatesView
+		groups={dupesQuery.data ?? []}
+		pending={dupesQuery.isPending}
+		error={dupesQuery.error}
+	/>
+</main>