fix(data): recalibrate checkpoint counters after cleanup

[Ricky-7-Yan]

Description | 描述

Recalibrates drift-prone checkpoint counters from actual persisted data so cleanup/manual pruning no longer leaves recall_checkpoint.json overstating memory totals.

Related Issue | 关联 Issue

Closes #157

Change Type | 修改类型

• Bug fix
• Data consistency improvement
• Tests added

Self-test Checklist | 自测清单

• Added CheckpointManager.recalibrateCounters() with VectorStore counts and JSONL fallback
• Recalibrates counters after local cleanup removes JSONL/VectorStore data
• Recalibrates once during store startup so existing drift self-heals
• Caps memories_since_last_persona to the recalibrated L1 total
• Added unit coverage for JSONL fallback and VectorStore-preferred counts

Verification | 验证

• npx.cmd vitest run src/utils/checkpoint.test.ts
• npm.cmd run build
• git diff --check

[Maxwell-Code07]

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