fix: remove duplicate 'Powered by Crewli' footer on registration pages

The portal layout already renders the footer — the inline copies in
[eventSlug].vue and success.vue caused it to appear twice.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

apps/portal/src/pages/register/[eventSlug].vue

@@ -1603,10 +1603,6 @@ async function onSubmit() {
         </VCol>
       </VRow>
 
-      <!-- Footer -->
-      <div class="text-center pa-4 text-caption text-medium-emphasis">
-        Powered by Crewli
-      </div>
     </VContainer>
   </div>
 </template>

apps/portal/src/pages/register/success.vue

@@ -132,10 +132,6 @@ const hasExistingAccount = computed(() => route.query.hasAccount === '1' && !isA
         </VBtn>
       </VAlert>
 
-      <!-- Footer -->
-      <div class="text-center pa-4 text-caption text-medium-emphasis">
-        Powered by Crewli
-      </div>
     </VContainer>
   </div>
 </template>