feat(person): add a curator "Ereignis für diese Person" link to PersonCard

A curator on a person's page can now seed a timeline event from that
person: a gated link to #781's /zeitstrahl/events/new?personId={id},
which prefills the person and returns to /persons/{id} on save. Hidden
for a Reader. New i18n key person_add_event in de/en/es.

Refs #842
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/routes/persons/[id]/PersonCard.svelte

@@ -128,7 +128,8 @@ const deathText = $derived(formatLifeDate(person.deathDate, person.deathDatePrec
 			</div>
 		{/if}
 
-		<!-- Edit button — full width, outlined -->
+		<!-- Curator actions — full width, outlined. Both links are gated to
+		     WRITE_ALL; the gate is UX only (the #781 route guard is the boundary). -->
 		{#if canWrite}
 			<a
 				href="/persons/{person.id}/edit"
@@ -142,6 +143,15 @@ const deathText = $derived(formatLifeDate(person.deathDate, person.deathDatePrec
 				/>
 				{m.btn_edit()}
 			</a>
+			<!-- Opens #781's create form pre-seeded with this person; on save it
+			     returns to /persons/{id} (originPersonId). #842 REQ-003/010. -->
+			<a
+				data-testid="person-add-event"
+				href="/zeitstrahl/events/new?personId={person.id}"
+				class="mt-2 flex min-h-[44px] w-full items-center justify-center gap-1.5 rounded border border-line px-3 py-2 font-sans text-xs font-bold tracking-widest text-ink-2 uppercase transition-colors hover:border-primary hover:text-ink"
+			>
+				{m.person_add_event()}
+			</a>
 		{/if}
 	</div>
 </div>