Add organizer-only attendee list to event detail view (011)

New GET /events/{token}/attendees endpoint returns attendee names when
a valid organizer token is provided (403 otherwise). The frontend
conditionally renders the list below the attendee count for organizers,
silently degrading for visitors.

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

backend/src/test/java/de/fete/adapter/in/web/EventControllerIntegrationTest.java

@@ -439,6 +439,68 @@ class EventControllerIntegrationTest {
     assertThat(rsvpJpaRepository.count()).isEqualTo(countBefore);
   }
 
+  // --- GET /events/{token}/attendees tests ---
+
+  @Test
+  void getAttendeesReturnsNamesForOrganizer() throws Exception {
+    EventJpaEntity event = seedEvent(
+        "Party", null, "Europe/Berlin", null,
+        LocalDate.now().plusDays(30));
+    seedRsvp(event, "Alice");
+    seedRsvp(event, "Bob");
+
+    mockMvc.perform(get("/api/events/" + event.getEventToken()
+            + "/attendees?organizerToken=" + event.getOrganizerToken()))
+        .andExpect(status().isOk())
+        .andExpect(jsonPath("$.attendees").isArray())
+        .andExpect(jsonPath("$.attendees.length()").value(2))
+        .andExpect(jsonPath("$.attendees[0].name").value("Alice"))
+        .andExpect(jsonPath("$.attendees[1].name").value("Bob"));
+  }
+
+  @Test
+  void getAttendeesReturnsEmptyListWhenNoRsvps() throws Exception {
+    EventJpaEntity event = seedEvent(
+        "Empty Party", null, "Europe/Berlin", null,
+        LocalDate.now().plusDays(30));
+
+    mockMvc.perform(get("/api/events/" + event.getEventToken()
+            + "/attendees?organizerToken=" + event.getOrganizerToken()))
+        .andExpect(status().isOk())
+        .andExpect(jsonPath("$.attendees").isArray())
+        .andExpect(jsonPath("$.attendees.length()").value(0));
+  }
+
+  @Test
+  void getAttendeesReturns403ForInvalidOrganizerToken() throws Exception {
+    EventJpaEntity event = seedEvent(
+        "Secret Party", null, "Europe/Berlin", null,
+        LocalDate.now().plusDays(30));
+
+    mockMvc.perform(get("/api/events/" + event.getEventToken()
+            + "/attendees?organizerToken=" + UUID.randomUUID()))
+        .andExpect(status().isForbidden())
+        .andExpect(content().contentTypeCompatibleWith(
+            "application/problem+json"));
+  }
+
+  @Test
+  void getAttendeesReturns404ForUnknownEvent() throws Exception {
+    mockMvc.perform(get("/api/events/" + UUID.randomUUID()
+            + "/attendees?organizerToken=" + UUID.randomUUID()))
+        .andExpect(status().isNotFound())
+        .andExpect(content().contentTypeCompatibleWith(
+            "application/problem+json"));
+  }
+
+  private void seedRsvp(EventJpaEntity event, String name) {
+    var rsvp = new RsvpJpaEntity();
+    rsvp.setRsvpToken(UUID.randomUUID());
+    rsvp.setEventId(event.getId());
+    rsvp.setName(name);
+    rsvpJpaRepository.save(rsvp);
+  }
+
   private EventJpaEntity seedEvent(
       String title, String description, String timezone,
       String location, LocalDate expiryDate) {

backend/src/test/java/de/fete/application/service/RsvpServiceTest.java

@@ -10,6 +10,7 @@ import de.fete.domain.model.Event;
 import de.fete.domain.model.EventToken;
 import de.fete.domain.model.OrganizerToken;
 import de.fete.domain.model.Rsvp;
+import de.fete.domain.model.RsvpToken;
 import de.fete.domain.port.out.EventRepository;
 import de.fete.domain.port.out.RsvpRepository;
 import java.time.Clock;
@@ -18,6 +19,7 @@ import java.time.LocalDate;
 import java.time.OffsetDateTime;
 import java.time.ZoneId;
 import java.time.ZoneOffset;
+import java.util.List;
 import java.util.Optional;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
@@ -122,6 +124,73 @@ class RsvpServiceTest {
         .isInstanceOf(EventExpiredException.class);
   }
 
+  @Test
+  void getAttendeeNamesReturnsNamesInOrder() {
+    Event event = buildActiveEvent();
+    EventToken token = event.getEventToken();
+    OrganizerToken orgToken = event.getOrganizerToken();
+    when(eventRepository.findByEventToken(token))
+        .thenReturn(Optional.of(event));
+    when(rsvpRepository.findByEventId(event.getId()))
+        .thenReturn(List.of(
+            buildRsvp(1L, "Alice"),
+            buildRsvp(2L, "Bob"),
+            buildRsvp(3L, "Charlie")));
+
+    List<String> names = rsvpService.getAttendeeNames(token, orgToken);
+
+    assertThat(names).containsExactly("Alice", "Bob", "Charlie");
+  }
+
+  @Test
+  void getAttendeeNamesReturnsEmptyListWhenNoRsvps() {
+    Event event = buildActiveEvent();
+    EventToken token = event.getEventToken();
+    OrganizerToken orgToken = event.getOrganizerToken();
+    when(eventRepository.findByEventToken(token))
+        .thenReturn(Optional.of(event));
+    when(rsvpRepository.findByEventId(event.getId()))
+        .thenReturn(List.of());
+
+    List<String> names = rsvpService.getAttendeeNames(token, orgToken);
+
+    assertThat(names).isEmpty();
+  }
+
+  @Test
+  void getAttendeeNamesThrowsWhenEventNotFound() {
+    EventToken token = EventToken.generate();
+    OrganizerToken orgToken = OrganizerToken.generate();
+    when(eventRepository.findByEventToken(token))
+        .thenReturn(Optional.empty());
+
+    assertThatThrownBy(
+        () -> rsvpService.getAttendeeNames(token, orgToken))
+        .isInstanceOf(EventNotFoundException.class);
+  }
+
+  @Test
+  void getAttendeeNamesThrowsWhenOrganizerTokenInvalid() {
+    Event event = buildActiveEvent();
+    EventToken token = event.getEventToken();
+    OrganizerToken wrongToken = OrganizerToken.generate();
+    when(eventRepository.findByEventToken(token))
+        .thenReturn(Optional.of(event));
+
+    assertThatThrownBy(
+        () -> rsvpService.getAttendeeNames(token, wrongToken))
+        .isInstanceOf(InvalidOrganizerTokenException.class);
+  }
+
+  private Rsvp buildRsvp(Long id, String name) {
+    var rsvp = new Rsvp();
+    rsvp.setId(id);
+    rsvp.setRsvpToken(RsvpToken.generate());
+    rsvp.setEventId(1L);
+    rsvp.setName(name);
+    return rsvp;
+  }
+
   private Event buildActiveEvent() {
     var event = new Event();
     event.setId(1L);