feat: add memory CLI utilities

[Viperdk2020]

Summary

• add memory CLI with migrate and compact commands
• compact JSONL memory files and migrate to SQLite with progress output
• test memory CLI commands on sample data

Testing

• cargo test -p codex-memory
• cargo test -p codex-cli

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https://chatgpt.com/codex/tasks/task_e_68b510a35750832985e4bcdf376de524

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