[@corbits/codex-provider] publish-prep: semver deps + dist build

[TheGreatAxios]

Publish-prep for @corbits/codex-provider: semver npm ranges for @corbits/oauth-core and @corbits/openai-responses, plus a compiled dist build (tsconfig.build.json, build/prepack, intx-src/types/default exports triple, dist-only files) with explicit .js relative imports in src and no rewrite scripts.

Verification:

• bun run build exit 0; dist/*.js + *.d.ts emitted, tests excluded
• bun run check (typecheck + lint + format:check + test) passes, 12/12 tests
• bun pm pack contains dist + README + LICENSE + package.json, no src
• consumer install of the packed tarball succeeds with git disabled (git shimmed to fail); deps resolved from their packed 0.1.0 tarballs via overrides
• node v24 probe importing the packed dist succeeds (oauth config, bridge message, hostile id_token, adapter factory, content-type repair)

Note: bun.lock regen against the npm registry is pending the @corbits/oauth-core and @corbits/openai-responses 0.1.0 publishes (both 404 today); do not merge until those land and CI resolves.

Fixes CL-8948