fix(ui): switch alias operations from client fetch to form actions

Replaces raw client-side fetch with SvelteKit form actions
(addAlias, removeAlias) using the server-side API client for
proper auth handling. 10 new component tests for NameHistoryEditCard.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/routes/persons/[id]/edit/+page.svelte

@@ -51,12 +51,7 @@ const person = $derived(data.person);
 		</div>
 	</form>
 
-	<NameHistoryEditCard
-		personId={person.id}
-		personFirstName={person.firstName}
-		aliases={data.aliases}
-		canWrite={true}
-	/>
+	<NameHistoryEditCard aliases={data.aliases} canWrite={true} aliasError={form?.aliasError} />
 
 	<PersonDangerZone person={person} form={form} />