fix(immich): remove album photos on unlink

When unlinking an Immich album, photos synced from that album are now
deleted. A new `album_link_id` FK column on `trip_photos` tracks the
source album link at sync time; `deleteAlbumLink` deletes matching
photos before removing the link. Individually-added photos are
unaffected. The client now refreshes the photo grid after unlinking.

Adds integration tests IMMICH-020 through IMMICH-024.

Closes #398

client/src/components/Memories/MemoriesPanel.tsx

@@ -107,7 +107,8 @@ export default function MemoriesPanel({ tripId, startDate, endDate }: MemoriesPa
   const unlinkAlbum = async (linkId: number) => {
     try {
       await apiClient.delete(`/integrations/immich/trips/${tripId}/album-links/${linkId}`)
-      loadAlbumLinks()
+      await loadAlbumLinks()
+      await loadPhotos()
     } catch { toast.error(t('memories.error.unlinkAlbum')) }
   }