fix(summer-camp): 四大原则卡片兼容对象格式({title,desc})

pages/summer-camp.vue

@@ -118,7 +118,11 @@
         <div class="principles-grid">
           <div v-for="(p, i) in camp.principles" :key="i" class="principle-card">
             <div class="principle-index">{{ String(i + 1).padStart(2, '0') }}</div>
-            <h3 class="principle-name">{{ p }}</h3>
+            <template v-if="p && typeof p === 'object'">
+              <h3 class="principle-name">{{ p.title }}</h3>
+              <p v-if="p.desc" class="principle-desc">{{ p.desc }}</p>
+            </template>
+            <h3 v-else class="principle-name">{{ p }}</h3>
           </div>
         </div>
       </div>
@@ -399,6 +403,13 @@ const campFAQ = computed(() => camp.value?.faq || [])
   font-weight: @font-weight-medium;
 }
 
+.principle-desc {
+  margin-top: @space-xs;
+  font-size: @font-size-sm;
+  color: @color-text-secondary;
+  line-height: 1.6;
+}
+
 // 行程概览
 .itinerary-list {
   max-width: 800px;