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/photo/[uid]/+page.svelte

@@ -0,0 +1,16 @@
+<script lang="ts">
+	import { goto } from '$app/navigation';
+	import { page } from '$app/state';
+	import { openPreview } from '$lib/stores/preview.svelte';
+
+	// Deep-link entry: opening /photo/<uid> directly pops the overlay on
+	// the timeline. The route itself does not render anything; it hands
+	// off to the global PreviewOverlay and redirects to `/` so the URL
+	// stays clean and the timeline shows behind the modal.
+	$effect(() => {
+		const uid = page.params.uid as string | undefined;
+		if (!uid) return;
+		openPreview(uid);
+		void goto('/', { replaceState: true });
+	});
+</script>