feat: 新增多语言文案并修复动态国际化调用问题

1. 新增多语言文件覆盖组件、页面、公共模块的翻译文案
2. 修复多处动态拼接lang key的调用，增加兜底逻辑避免空值或原始key暴露
3. 补全DIY组件、业务页面的国际化适配
4. 新增P2动态key国际化处理方案文档

components/ns-chat/ns-chat-goods.vue

@@ -9,7 +9,7 @@
 						<text class="goods-price-sign color-base-text">￥</text>
 						<text class="color-base-text">{{ goodsInfo.price }}</text>
 					</view>
-					<view class="goods-option font-size-goods-tag disabled">已发送</view>
+					<view class="goods-option font-size-goods-tag disabled">{{ $lang('components.chatGoods.sent') }}</view>
 				</view>
 			</view>
 		</view>
@@ -22,7 +22,7 @@
 						<text class="goods-price-sign color-base-text">￥</text>
 						<text class="color-base-text">{{ goodsDetail.price }}</text>
 					</view>
-					<view class="goods-option font-size-goods-tag color-base-bg" @click="sendMsg('goods')">发送</view>
+					<view class="goods-option font-size-goods-tag color-base-bg" @click="sendMsg('goods')">{{ $lang('components.chatGoods.send') }}</view>
 				</view>
 			</view>
 		</view>

components/ns-chat/ns-chat-receiveGoods.vue

@@ -5,8 +5,8 @@
 			<view class="goods-item">
 				<view class="title">{{ isEnEnv ? goodsInfo.en_goods_name : goodsInfo.goods_name }}</view>
 				<view class="goods-sku">
-					库存:{{ goodsInfo.stock }}
-					<text>销量:{{ goodsInfo.sale_num }}</text>
+					{{ $lang('components.chatReceiveGoods.stockPrefix') }}{{ goodsInfo.stock }}
+					<text>{{ $lang('components.chatReceiveGoods.salesPrefix') }}{{ goodsInfo.sale_num }}</text>
 				</view>
 				<view class="goods-price">
 					<view class="price color-base-text">
@@ -14,7 +14,7 @@
 						<text class="price-num">{{ goodsInfo.price }}</text>
 					</view>
 					<view class="see-shop color-base-text" @click="go_shop()">
-						查看商品
+						{{ $lang('components.chatReceiveGoods.viewGoods') }}
 						<text class="iconfont icon-right"></text>
 					</view>
 				</view>