chore: introduce new --native flag to Node module release process

[bolinfest]

This PR introduces an optional build flag, --native, that will build a version of the Codex npm module that:

• Includes both the Node.js and native Rust versions (for Mac and Linux)
• Will run the native version if CODEX_RUST=1 is set
• Runs the TypeScript version otherwise

Note this PR also updates the workflow URL to https://github.com/openai/codex/actions/runs/14872557396, as that is a build from today that includes everything up through #843.

Test Plan:

In ~/code/codex/codex-cli, I ran:

pnpm stage-release --native

The end of the output was:

Staged version 0.1.2505121317 for release in /var/folders/wm/f209bc1n2bd_r0jncn9s6j_00000gp/T/tmp.xd2p5ETYGN
Test Node:
    node /var/folders/wm/f209bc1n2bd_r0jncn9s6j_00000gp/T/tmp.xd2p5ETYGN/bin/codex.js --help
Test Rust:
    CODEX_RUST=1 node /var/folders/wm/f209bc1n2bd_r0jncn9s6j_00000gp/T/tmp.xd2p5ETYGN/bin/codex.js --help
Next:  cd "/var/folders/wm/f209bc1n2bd_r0jncn9s6j_00000gp/T/tmp.xd2p5ETYGN" && npm publish --tag native

I verified that running each of these commands ran the expected version of Codex.

While here, I also added bin to the files list in package.json, which should have been done as part of #757, as that added new entries to bin that were matched by .gitignore but should have been included in a release.

[bolinfest]

@fouad-openai do you want this to print something else if --native was passed to indicate publishing to a different tag?

[fouad-openai]

yeah maybe we should include a --tag for npm publish like --tag native or thinking something else?