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/messages/de.json

@@ -188,6 +188,7 @@
 	"person_hint_generation": "Generation in der Familie (G 0 = älteste Generation)",
 	"person_year_error": "Bitte eine vierstellige Jahreszahl eingeben",
 	"person_years_error_order": "Geburtsjahr muss vor dem Todesjahr liegen",
+	"person_add_event": "Ereignis für diese Person",
 	"person_docs_heading": "Gesendete Dokumente",
 	"person_no_docs": "Diese Person ist noch nicht als Absender verknüpft.",
 	"person_received_docs_heading": "Empfangene Dokumente",

frontend/messages/en.json

@@ -188,6 +188,7 @@
 	"person_hint_generation": "Generation within the family (G 0 = oldest generation)",
 	"person_year_error": "Please enter a four-digit year",
 	"person_years_error_order": "Birth year must be before death year",
+	"person_add_event": "Add event for this person",
 	"person_docs_heading": "Sent documents",
 	"person_no_docs": "This person has not yet been linked as a sender.",
 	"person_received_docs_heading": "Received documents",

frontend/messages/es.json

@@ -188,6 +188,7 @@
 	"person_hint_generation": "Generación dentro de la familia (G 0 = generación más antigua)",
 	"person_year_error": "Introduzca un año de cuatro dígitos",
 	"person_years_error_order": "El año de nacimiento debe ser anterior al año de fallecimiento",
+	"person_add_event": "Añadir evento para esta persona",
 	"person_docs_heading": "Documentos enviados",
 	"person_no_docs": "Esta persona aún no está vinculada como remitente.",
 	"person_received_docs_heading": "Documentos recibidos",

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>

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

@@ -0,0 +1,32 @@
+import { describe, it, expect, afterEach } from 'vitest';
+import { cleanup, render } from 'vitest-browser-svelte';
+import PersonCard from './PersonCard.svelte';
+
+afterEach(() => cleanup());
+
+const PERSON_ID = '55555555-5555-5555-5555-555555555555';
+
+const makePerson = (overrides = {}) => ({
+	id: PERSON_ID,
+	firstName: 'Karl',
+	lastName: 'Raddatz',
+	displayName: 'Karl Raddatz',
+	personType: 'PERSON',
+	...overrides
+});
+
+describe('PersonCard add-event affordance (#842)', () => {
+	it('shows an add-event link pre-seeded with the person to a curator (REQ-003)', () => {
+		render(PersonCard, { person: makePerson(), canWrite: true });
+		const add = document.querySelector(
+			'[data-testid="person-add-event"]'
+		) as HTMLAnchorElement | null;
+		expect(add).not.toBeNull();
+		expect(add?.getAttribute('href')).toBe(`/zeitstrahl/events/new?personId=${PERSON_ID}`);
+	});
+
+	it('renders no add-event link to a reader (REQ-004)', () => {
+		render(PersonCard, { person: makePerson(), canWrite: false });
+		expect(document.querySelector('[data-testid="person-add-event"]')).toBeNull();
+	});
+});