feat(cli): add memory subcommand and tests

[Viperdk2020]

Summary

• add memory CLI subcommand wired to new handler
• implement memory operations backed by codex-memory
• test argument parsing and JSONL/SQLite store happy paths

Testing

• cargo clippy -p codex-cli (failed: variables can be used directly in the format string)
• cargo test -p codex-cli

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https://chatgpt.com/codex/tasks/task_e_68b5109fead4832991ac5c08e5da4ab8

[github-actions]

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