feat(merch/detail): add long press to show full merchant description

add longpress event handler to display full merch desc in a modal when triggered

pages_promotion/merch/detail.vue

@@ -23,7 +23,7 @@
 						<text class="icox icox-xing"></text>
 						<text class="icox icox-xing"></text>
 					</view>
-					<view style="overflow:hidden;text-overflow:ellipsis;display:-webkit-box;-webkit-line-clamp:2;-webkit-box-orient:vertical;">{{ merch.desc }}</view>
+					<view style="overflow:hidden;text-overflow:ellipsis;display:-webkit-box;-webkit-line-clamp:2;-webkit-box-orient:vertical;" @longpress="showFullDesc">{{ merch.desc }}</view>
 				</view>
 
 			</view>
@@ -337,6 +337,15 @@ export default {
 		}
 	},
 	methods: {
+		showFullDesc() {
+			if (this.merch.desc) {
+				uni.showModal({
+					title: '商家描述',
+					content: this.merch.desc,
+					showCancel: false
+				});
+			}
+		},
 		initHeaderHeight() {
 			setTimeout(() => {
 				const query = uni.createSelectorQuery().in(this);