fix(frontend): sort a file's assigned tags by the chosen tag order

The file viewer's assigned-tags list showed tags in API order, ignoring the
sort the user picked on the tags page. Add a client-side sortTags helper and
order the assigned list (in TagPicker) by tagSorting, reactively so it re-sorts
the moment the sort changes.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/lib/api/tags.ts

@@ -1,7 +1,7 @@
 import { get } from 'svelte/store';
 import { api } from '$lib/api/client';
 import type { Tag, TagOffsetPage } from '$lib/api/types';
-import { tagSorting } from '$lib/stores/sorting';
+import { tagSorting, type SortState, type TagSortField } from '$lib/stores/sorting';
 
 // The /tags endpoint caps limit at 200 per request. Pickers and the filter bar
 // filter the tag list client-side, so they need the *whole* list — otherwise
@@ -28,3 +28,31 @@ export async function fetchAllTags(): Promise<Tag[]> {
 	}
 	return all;
 }
+
+// Field a tag is keyed on for a given sort choice. created_at is an ISO string,
+// so lexical comparison matches chronological order.
+function tagSortKey(t: Tag, field: TagSortField): string {
+	switch (field) {
+		case 'name':
+			return t.name ?? '';
+		case 'color':
+			return t.color ?? '';
+		case 'category_name':
+			return t.category_name ?? '';
+		case 'created':
+			return t.created_at ?? '';
+		default:
+			return '';
+	}
+}
+
+/**
+ * Returns a copy of `tags` sorted by the given tag sort state — used to order a
+ * file's already-assigned tags the same way as the tags page and the pickers'
+ * available list (which the server sorts). Client-side so it reacts instantly
+ * when the user changes the sort.
+ */
+export function sortTags(tags: Tag[], { sort, order }: SortState<TagSortField>): Tag[] {
+	const dir = order === 'asc' ? 1 : -1;
+	return [...tags].sort((a, b) => dir * tagSortKey(a, sort).localeCompare(tagSortKey(b, sort)));
+}

frontend/src/lib/components/file/TagPicker.svelte

@@ -1,6 +1,7 @@
 <script lang="ts">
 	import type { Tag } from '$lib/api/types';
-	import { fetchAllTags } from '$lib/api/tags';
+	import { fetchAllTags, sortTags } from '$lib/api/tags';
+	import { tagSorting } from '$lib/stores/sorting';
 
 	interface Props {
 		fileTags: Tag[];
@@ -30,10 +31,13 @@
 		)
 	);
 
+	// Show a file's already-assigned tags in the user's chosen tag order too.
+	let sortedAssigned = $derived(sortTags(fileTags, $tagSorting));
+
 	let filteredAssigned = $derived(
 		search.trim()
-			? fileTags.filter((t) => t.name?.toLowerCase().includes(search.toLowerCase()))
-			: fileTags
+			? sortedAssigned.filter((t) => t.name?.toLowerCase().includes(search.toLowerCase()))
+			: sortedAssigned
 	);
 
 	async function handleAdd(tagId: string) {