feat(recall): add optional remote rerank

[RerankerGuo]

Description | 描述

Add a narrow, default-off remote rerank step for auto-recalled L1 memories.

The recall pipeline still runs the existing keyword / embedding / hybrid search first. When recall.rerank.enabled is configured with a baseUrl, apiKey, and model, the plugin calls ${baseUrl}/rerank with the initial recalled candidates and reorders them by the returned index / relevance_score values before applying recall character budgets.

This keeps the feature conservative:

• Existing deployments are unchanged because rerank is disabled by default.
• Search still works when rerank is unavailable.
• HTTP errors, malformed responses, incomplete config, and timeout failures keep the original recall order.
• The request has a short independent timeout (recall.rerank.timeoutMs, default 1000ms) so rerank cannot block the broader recall path for long.

Related Issue | 关联 Issue

Fix #3

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

Verification | 验证

• npx vitest run src/core/recall/rerank.test.ts
• npm test
• npm run build
• git diff --check

Additional Notes | 其他说明

The implementation intentionally targets auto-recall only as a first step, because that is where irrelevant top-K memories directly enter prompt context. Agent-initiated tdai_memory_search can remain deterministic and inspectable unless maintainers want rerank applied there as a follow-up.

[Maxwell-Code07]

Thanks for your attention! We’ll review this and get back to you as soon as possible.