Support ChatGPT Library file tools

[lt-oai]

Summary

• Allow connector_openai_library through Codex apps connector filtering.
• Support store_in_library file uploads by calling /files/process_upload_stream after the file bytes upload
• Propagate library_file_id into uploaded MCP file arguments.
• Add an after mcp_tool call hook to materialize file download link if the materialize_file_download key exists in tool results meta

Companion PR

• https://github.com/openai/openai/pull/854887
• https://github.com/openai/openai/pull/854888

Tests

• Tested against production backend

output.mp4

• cargo fmt
• cargo test -p codex-api upload_local_file_stores_library_file_with_process_upload_stream
• cargo test -p codex-mcp codex_apps_tools_cache_filters_disallowed_connectors
• cargo test -p codex-core build_uploaded_local_argument_value_uploads_local_file_path