fix(recall): stabilize prompt-cache memory injection

[Ricky-7-Yan]

Description | 描述

Fixes #120.

Add explicit prompt-cache controls for TencentDB recall injection while keeping the default behavior backward compatible.

This PR keeps the TencentDB-side mitigation scoped:

• Add recall.injectionMode with prepend as the backward-compatible default
• Add opt-in append mode that emits dynamic L1 recall as OpenClaw appendContext
• Add recall.showInjected so preserving <relevant-memories> in persisted history is explicit opt-in
• Keep persisted history clean by default to avoid replaying stale dynamic recall blocks
• Move OpenClaw recall shaping and injected-history stripping into a tested adapter helper
• Document both options in the plugin manifest and README files

Cache impact | 缓存影响

• Stable memory context remains in appendSystemContext
• Dynamic L1 recall can stay out of the user prompt prefix with recall.injectionMode="append" on compatible OpenClaw hosts
• Persisted history avoids dynamic recall growth by default with recall.showInjected=false

Related Issue | 关联 Issue

Fix #120

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.cmd vitest run src/config.test.ts src/adapters/openclaw/recall-injection.test.ts
npx.cmd vitest run
npm.cmd run build
git diff --check

Results:

• Targeted tests: 2 files / 8 tests passed
• Full test suite: 6 files / 75 tests passed
• Build passed
• Whitespace check passed

[Maxwell-Code07]

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