Add app-server support for spawn_agents_on_csv

[khai-oai]

Summary

• add model and reasoning_effort support to spawn_agents_on_csv
• propagate batch-spawn tool metadata through protocol, app-server, exec, and TUI surfaces
• add app-server/TUI/exec coverage for the new batch collab item shape and worker statuses

Local validation

• cargo test -p codex-tools
• cargo test -p codex-protocol
• cargo test -p codex-app-server-protocol
• cargo test -p codex-tui
• cargo test -p codex-app-server turn_start_emits_spawn_agents_on_csv_item_with_model_metadata_v2
• cargo test -p codex-exec collab_batch_spawn_begin_and_end_emit_item_events
• just fmt
• just fix -p codex-core

Notes

• cargo test -p codex-app-server still has unrelated local failures in auth/conversation-summary/fuzzy-search tests plus one unrelated analytics-gating failure.
• earlier local cargo test -p codex-exec hit an unrelated existing failure in tests::thread_start_params_include_review_policy_when_review_policy_is_manual_only.

[github-actions]

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

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1 out of 2 committers have signed the CLA.
✅ (khai-oai)[https://github.com/khai-oai]
❌ @rupert-openai
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