fix(conversation): add missing columns to match evolution-service schema

Add columns that evolution-service defines to prevent synchronize:true
from trying to drop them:
- userMessageCount, assistantMessageCount
- totalInputTokens, totalOutputTokens
- rating, feedback, hasConverted

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

packages/services/conversation-service/src/domain/entities/conversation.entity.ts

@@ -83,6 +83,29 @@ export class ConversationEntity {
   @Column({ name: 'message_count', default: 0 })
   messageCount: number;
 
+  // ========== 统计字段（与evolution-service保持一致）==========
+
+  @Column({ name: 'user_message_count', default: 0 })
+  userMessageCount: number;
+
+  @Column({ name: 'assistant_message_count', default: 0 })
+  assistantMessageCount: number;
+
+  @Column({ name: 'total_input_tokens', default: 0 })
+  totalInputTokens: number;
+
+  @Column({ name: 'total_output_tokens', default: 0 })
+  totalOutputTokens: number;
+
+  @Column({ type: 'smallint', nullable: true })
+  rating: number;
+
+  @Column({ type: 'text', nullable: true })
+  feedback: string;
+
+  @Column({ name: 'has_converted', default: false })
+  hasConverted: boolean;
+
   // ========== V2新增：咨询流程字段 ==========
 
   /**