refactor(i18n): 完成全量硬编码中文文案替换为多语言方案

1.  替换所有页面/组件中的硬编码中文提示文案为$lang调用，包括支付、帮助中心、公告等页面
2.  重构diy.js加载失败文案处理逻辑，支持参数化替换
3.  新增多语言混入逻辑，实现导航标题随语种动态切换
4.  重构支付组件初始化逻辑，优化平台适配代码
5.  添加多语言单元测试和硬编码扫描脚本
6.  更新语言包，新增缺失的翻译词条

scripts/lang_audit_report_v2.json

@@ -1,14 +1,77 @@
 {
-  "bundle_version": "1782901586",
+  "bundle_version": "1784767380",
   "bundle_lang": "zh-cn",
-  "bundle_leaves": 2649,
-  "code_calls_total": 2677,
-  "code_unique_keys": 2083,
-  "found_in_bundle": 2082,
+  "bundle_leaves": 2659,
+  "code_calls_total": 2693,
+  "code_unique_keys": 2097,
+  "found_in_bundle": 2086,
   "missing_summary": {
+    "TRULY_MISSING": 12,
     "SYNTAX_BUG": 1
   },
   "missing_classified": {
+    "TRULY_MISSING": [
+      {
+        "key": "common.buyNow",
+        "file": "components\\ns-goods-recommend\\ns-goods-recommend.vue",
+        "reason": "not in bundle, not local"
+      },
+      {
+        "key": "wechatChannel.wechatMpOnly",
+        "file": "components-diy\\diy-channel-list.vue",
+        "reason": "not in bundle, not local"
+      },
+      {
+        "key": "common.submitSuccess",
+        "file": "components-diy\\diy-form.vue",
+        "reason": "not in bundle, not local"
+      },
+      {
+        "key": "submitFail",
+        "file": "components-diy\\diy-form.vue",
+        "reason": "not in bundle, not local"
+      },
+      {
+        "key": "diy.networkError",
+        "file": "pages\\index\\index.vue",
+        "reason": "not in bundle, not local"
+      },
+      {
+        "key": "versionInfo",
+        "file": "pages\\index\\public\\js\\index.js",
+        "reason": "not in bundle, not local"
+      },
+      {
+        "key": "commitId",
+        "file": "pages\\index\\public\\js\\index.js",
+        "reason": "not in bundle, not local"
+      },
+      {
+        "key": "buildTime",
+        "file": "pages\\index\\public\\js\\index.js",
+        "reason": "not in bundle, not local"
+      },
+      {
+        "key": "diy.networkError",
+        "file": "pages_goods\\category.vue",
+        "reason": "not in bundle, not local"
+      },
+      {
+        "key": "goods.detail.formEmptyTip",
+        "file": "pages_goods\\detail.vue",
+        "reason": "not in bundle, not local"
+      },
+      {
+        "key": "common.buyNow",
+        "file": "pages_goods\\public\\js\\list.js",
+        "reason": "not in bundle, not local"
+      },
+      {
+        "key": "pay.index.payInfoNotFound",
+        "file": "pages_tool\\pay\\index.vue",
+        "reason": "not in bundle, not local"
+      }
+    ],
     "SYNTAX_BUG": [
       {
         "key": "order.list.status.",
@@ -19,18 +82,8 @@
   },
   "placeholder_issues": [],
   "data_lang_issues": {
-    "components\\ns-payment\\ns-payment.vue": [
-      "components.nsPayment.alipay"
-    ],
     "pages_promotion\\fenxiao\\apply.vue": [
       "fenxiao.apply.pleaseEnterName"
-    ],
-    "pages_promotion\\merch\\public\\js\\list.js": [
-      "merch.list.buyText"
-    ],
-    "pages_tool\\ai-chat\\ai-chat-message.vue": [
-      "ai-chat.index.loadMoreHistory",
-      "ai-chat.index.defaultNickname"
     ]
   },
   "hardcoded_navbar_titles": [
@@ -121,6 +174,11 @@
     "common.tabBar.cart",
     "common.tabBar.member"
   ],
-  "local_only_keys": [],
+  "local_only_keys": [
+    "buildTime",
+    "commitId",
+    "submitFail",
+    "versionInfo"
+  ],
   "bundle_only_keys_in_unique": []
 }