fix(record): retry unparsable L1 extraction output

[RerankerGuo]

Description | 描述

Retry L1 extraction once when the model returns output that cannot be parsed as the required JSON array.

• Keeps valid empty extraction results ([]) as-is and does not retry them.
• Reuses the same extraction prompt with an additional retry instruction that asks for JSON only.
• Adds focused coverage for parse-failure retry success and for not retrying a valid empty array.

Related Issue | 关联 Issue

Fix #115

Change Type | 修改类型

• Bug fix | Bug 修复
• New feature | 新功能
• Documentation update | 文档更新
• Code optimization | 代码优化

Self-test Checklist | 自测清单

• Verified locally | 本地验证通过
• No existing features affected | 无影响现有功能

Additional Notes | 其他说明

Verified with npx vitest run src/core/record/l1-extractor.test.ts, npm test, and npm run build using Node v24.15.0.

[Maxwell-Code07]

Retrying on parse failure is a pragmatic improvement for L1 extraction reliability. We appreciate the care taken to not retry valid empty results. We'll review it internally.