web: de-brand PhotoPrism references in user-facing copy

Replaces "PhotoPrism" in UI strings (empty states, tooltips, toasts,
log header, login screen) with neutral terms like "the indexer", "the
library", "the server" — accurate regardless of backend. The login
header becomes "Mulimage" and drops the explicit PhotoPrism mention.

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

web/src/lib/components/duplicates/CrossFolderGroupCard.svelte

@@ -158,7 +158,7 @@
 					`Archived ${result.moved.length} duplicate${result.moved.length === 1 ? '' : 's'}`,
 					{
 						description: losingIndexed
-							? 'The previously-indexed copy was moved; PhotoPrism will drop it on the next index pass.'
+							? 'The previously-indexed copy was moved; the indexer will drop it on the next index pass.'
 							: 'Files moved to .duplicates/ inside originals.'
 					}
 				);
@@ -246,7 +246,7 @@
 					{#if isIndexed}
 						<span
 							class="absolute right-1.5 top-1.5 rounded bg-emerald-600 px-1.5 py-0.5 text-[10px] font-semibold text-white"
-							title="Currently indexed by PhotoPrism"
+							title="Currently in the library"
 						>
 							Indexed
 						</span>