fix(codex): read text-block custom tool output

[lixenstrand]

Summary

• accept both legacy string output and current Codex text-block arrays for custom tool calls
• join text blocks into the raw action output without changing TDD policy
• cover both transcript formats and a Vitest failure used as Red evidence

Tests

• npx vitest run src/vendors/codex/transcript.test.ts src/cli.test.ts -t 'reads custom tool output|passes Codex Vitest text-block output' — 2 passed, 20 skipped
• npm run checks — 58 test files passed; 539 tests passed, 26 skipped

[nizos]

Hi @lixenstrand,

Thanks for the PR. I will try to look at it as soon as I can. Might take a few days to a week. :)