fix(order-service): 修复包含 Emoji 和孤立代理字符的订单在 PostgreSQL jsonb 下报错导致死循环重试进单的问题

1. 在 utils/json.ts 新增 sanitizeWellFormedUnicode、deepSanitizeUnicode 和 safeJsonStringify，自动清理空字节 (\0) 并将畸变孤立 UTF-16 代理字符 (Lone Surrogates) 安全转换为规范字符，杜绝 PostgreSQL jsonb 解析错误；
2. 拼多多订单映射器与通用进单服务 (order-service) 全面接入 Unicode 深度清洗与安全序列化，确保买家昵称/留言中的各类特殊 Emoji 和生僻字符平滑落库；
3. 数据库仓储层 (order-repo / order-item-repo) 针对 raw_payload_json、spec_json、item_snapshot_json 等 jsonb 字段增加兜底安全序列化保护；
4. 补充 utils/json.test.ts 与 pdd-order-mapper.test.ts 单元测试，覆盖畸变字符与空字节场景。

apps/backend/src/utils/json.ts

@@ -64,6 +64,66 @@ function shouldPreserveIntegerToken(rawDigits: unknown): boolean {
   return unsigned > '9007199254740991'
 }
 
+export function sanitizeWellFormedUnicode(value: unknown): string {
+  if (value === null || value === undefined) return ''
+  const str = String(value)
+  if (!str) return ''
+  // 1. Remove null bytes (\u0000) which PostgreSQL text/jsonb columns strictly forbid
+  const withoutNull = str.replace(/\0/g, '')
+  // 2. Convert lone surrogates into replacement character U+FFFD
+  const toWellFormedFn = (withoutNull as { toWellFormed?: () => string }).toWellFormed
+  return typeof toWellFormedFn === 'function'
+    ? toWellFormedFn.call(withoutNull)
+    : withoutNull.replace(
+        /[\uD800-\uDBFF](?![\uDC00-\uDFFF])|(?<![\uD800-\uDBFF])[\uDC00-\uDFFF]/g,
+        '\uFFFD',
+      )
+}
+
+export function deepSanitizeUnicode<T>(value: T): T {
+  if (value === null || value === undefined) {
+    return value
+  }
+  if (typeof value === 'string') {
+    return sanitizeWellFormedUnicode(value) as unknown as T
+  }
+  if (Array.isArray(value)) {
+    return value.map((item) => deepSanitizeUnicode(item)) as unknown as T
+  }
+  if (isPlainObject(value)) {
+    const res: Record<string, unknown> = {}
+    for (const [k, v] of Object.entries(value)) {
+      const cleanKey = sanitizeWellFormedUnicode(k)
+      res[cleanKey] = deepSanitizeUnicode(v)
+    }
+    return res as unknown as T
+  }
+  return value
+}
+
+export function safeJsonStringify(value: unknown, fallback = '{}'): string {
+  if (value === undefined || value === null) {
+    return fallback
+  }
+  if (typeof value === 'string') {
+    const trimmed = value.trim()
+    if (!trimmed) return fallback
+    try {
+      const parsed = JSON.parse(trimmed)
+      const sanitized = deepSanitizeUnicode(parsed)
+      return JSON.stringify(sanitized)
+    } catch {
+      return JSON.stringify(sanitizeWellFormedUnicode(value))
+    }
+  }
+  try {
+    const sanitized = deepSanitizeUnicode(value)
+    return JSON.stringify(sanitized)
+  } catch {
+    return fallback
+  }
+}
+
 function isPlainObject(value: unknown): value is JsonObject {
   return Object.prototype.toString.call(value) === '[object Object]'
 }