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/pick-regions/pick-regions.vue

@@ -14,8 +14,8 @@
         <uni-popup type="bottom" ref="regionsRef">
             <view class="regions-picker-container">
                 <view class="picker-header">
-                    <view class="picker-action cancel" @click="$refs.regionsRef.close()">取消</view>
-                    <view class="picker-action confirm" @click="confirmRegions">完成</view>
+                    <view class="picker-action cancel" @click="$refs.regionsRef.close()">{{ $lang('components.pickRegions.cancel') }}</view>
+                    <view class="picker-action confirm" @click="confirmRegions">{{ $lang('components.pickRegions.confirm') }}</view>
                 </view>
                 <picker-view :value="multiIndex" @change="pickerViewColumnChange" class="picker-view">
                     <picker-view-column v-if="multiArray[0]">