Tune memory read-path for stale facts

[andi-oai]

Why

• tighten Codex memory-read behavior around stale facts and conflicting memory
• encode the risk-of-drift vs verification-effort decision rule directly in the read-path prompt
• make partial stale-detail updates explicit so correcting only the answer is not treated as sufficient

What changed

• update codex-rs/core/templates/memories/read_path.md
• add guidance for when to verify cheap local facts vs when to answer from older memory with visible provenance
• strengthen same-turn MEMORY.md updates when stored concrete details are stale

Notes

• this is based on some staleness eval work

[github-actions]

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[andi-oai]

I have read the CLA Document and I hereby sign the CLA