Sync collaboration mode naming across Default prompt, tools, and TUI

[charley-oai]

Summary

• add shared ModeKind helpers for display names, TUI visibility, and request_user_input availability
• derive TUI mode filtering/labels from shared ModeKind metadata instead of local hardcoded matches
• derive request_user_input availability text and unavailable error mode names from shared mode metadata
• replace hardcoded known mode names in the Default collaboration-mode template with {{KNOWN_MODE_NAMES}} and fill it from TUI_VISIBLE_COLLABORATION_MODES
• add regression tests for mode metadata sync and placeholder replacement

Notes

• cargo test -p codex-core integration target (tests/all) still shows pre-existing env-specific failures in this environment due missing test_stdio_server binary resolution; core unit tests are green.

Codex author

codex resume 019c26ff-dfe7-7173-bc04-c9e1fff1e447

[charley-oai]

@codex review this

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. 🎉

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