fix(planting-service): 修复 fontkit 导入方式

使用 require 替代 ES import 解决 TypeScript 编译后 default export 问题

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

backend/services/planting-service/src/infrastructure/pdf/pdf-generator.service.ts

@@ -2,7 +2,9 @@ import { Injectable, Logger } from '@nestjs/common';
 import * as fs from 'fs';
 import * as path from 'path';
 import { PDFDocument, rgb } from 'pdf-lib';
-import fontkit from '@pdf-lib/fontkit';
+
+// eslint-disable-next-line @typescript-eslint/no-var-requires
+const fontkit = require('@pdf-lib/fontkit');
 
 /**
  * 合同 PDF 生成数据