fix(contribution-service): 修复CDC消息解析以支持Debezium扁平化格式

Debezium配置了ExtractNewRecordState转换，消息格式是扁平化的：
- 元数据字段使用__前缀（__op, __table, __source_ts_ms, __deleted）
- 业务数据字段直接在根级别
- 修改handleMessage方法正确解析扁平化格式
- 更新CDCEvent接口以匹配实际消息结构

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/services/contribution-service/src/infrastructure/kafka/cdc-consumer.service.ts

@@ -2,28 +2,32 @@ import { Injectable, Logger, OnModuleInit } from '@nestjs/common';
 import { ConfigService } from '@nestjs/config';
 import { Kafka, Consumer, EachMessagePayload } from 'kafkajs';
 
+/**
+ * CDC 事件接口
+ *
+ * 注意：由于 Debezium 配置了 ExtractNewRecordState 转换（unwrap），
+ * 消息格式是扁平化的，字段直接在根级别，元数据字段以 __ 为前缀。
+ *
+ * 扁平化格式示例：
+ * {
+ *   "order_id": 1,
+ *   "tree_count": 1,
+ *   "account_sequence": "D25122700015",
+ *   "__op": "c",
+ *   "__table": "planting_orders",
+ *   "__source_ts_ms": 1767892060857,
+ *   "__deleted": "false"
+ * }
+ */
 export interface CDCEvent {
-  schema: any;
+  // 为了兼容性，构造一个 payload 对象
   payload: {
+    op: 'c' | 'u' | 'd' | 'r'; // create, update, delete, read (snapshot)
     before: any | null;
     after: any | null;
-    source: {
-      version: string;
-      connector: string;
-      name: string;
-      ts_ms: number;
-      snapshot: string;
-      db: string;
-      sequence: string;
-      schema: string;
-      table: string;
-      txId: number;
-      lsn: number;
-      xmin: number | null;
-    };
-    op: 'c' | 'u' | 'd' | 'r'; // create, update, delete, read (snapshot)
-    ts_ms: number;
-    transaction: any;
+    table: string;
+    source_ts_ms: number;
+    deleted: boolean;
   };
   // 内部使用：Kafka offset 作为序列号
   sequenceNum: bigint;
@@ -133,21 +137,42 @@ export class CDCConsumerService implements OnModuleInit {
         return;
       }
 
-      const eventData = JSON.parse(message.value.toString());
+      const rawData = JSON.parse(message.value.toString());
+
+      // Debezium ExtractNewRecordState 转换后的扁平化格式
+      // 元数据字段: __op, __table, __source_ts_ms, __deleted
+      // 数据字段直接在根级别
+      const op = rawData.__op || rawData.op;
+      const table = rawData.__table;
+      const sourceTsMs = rawData.__source_ts_ms || 0;
+      const deleted = rawData.__deleted === 'true' || rawData.__deleted === true;
+
+      // 从原始数据中移除元数据字段，剩下的就是业务数据
+      const { __op, __table, __source_ts_ms, __deleted, ...businessData } = rawData;
+
+      // 构造兼容的 CDCEvent 对象
+      // 对于 create/update/read，数据在 after；对于 delete，数据在 before
       const event: CDCEvent = {
-        ...eventData,
+        payload: {
+          op: op as 'c' | 'u' | 'd' | 'r',
+          before: op === 'd' ? businessData : null,
+          after: op !== 'd' ? businessData : null,
+          table: table,
+          source_ts_ms: sourceTsMs,
+          deleted: deleted,
+        },
         sequenceNum: BigInt(message.offset),
       };
 
-      // 从 topic 名称提取表名
-      // 格式通常是: dbserver1.schema.tablename
+      // 从 topic 名称提取表名作为备选
+      // 格式: cdc.<service>.public.<table_name>
       const parts = topic.split('.');
-      const tableName = parts[parts.length - 1];
+      const tableName = table || parts[parts.length - 1];
 
       const handler = this.handlers.get(tableName);
       if (handler) {
         await handler(event);
-        this.logger.debug(`Processed CDC event for table ${tableName}, op: ${event.payload.op}`);
+        this.logger.debug(`Processed CDC event for table ${tableName}, op: ${op}`);
       } else {
         this.logger.warn(`No handler registered for table: ${tableName}`);
       }