fix: preserve coding-agent span origin after span closure

[Luca Forstner (lforst)]

• Fix late updates to completed trace spans losing their coding-agent identity and falling back to generic SDK metadata. Every update now includes the original agent name, plugin version, and instrumentation identity, including after recovery.
• Expand regression coverage across all six supported agents, checking that late and recovered updates preserve attribution and parent relationships, even when agents share an SDK client.

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-24T15:59:51.677323Z	edbcb29	Draft marked ready

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