Remove dead code behind old onboarding flag

Transcript

1. 00:00
   prompt · you818 tok

   Remove dead code behind old onboarding flag. Work in small steps and run the tests before you finish.

2. 05:00
   Tests green
3. 09:49
   Typecheck clean
4. 14:51
   Edit src/theme/tokens.css7.4s
5. 19:53
   Bash npm test6.5s
6. 24:43
   Edit src/api/rate-limit.ts4.0s
7. 29:51
   reasoning 1.8k tok
8. 34:48
   Assistant1.5k tok

   Reproduced it. The retry wrapper swallows the original error, so the log only shows the last attempt.

9. 39:46
   Bash git diff --stat1.6s
10. 44:38
    Write src/export/pipeline.ts0.5s
11. 49:35
    Assistant1.7k tok

    Two of the failures are ordering-dependent — the suite passes in isolation. Adding an explicit sort before the assertion.

12. 54:38
    Assistant344 tok

    Tests pass locally. Running the full suite once more before writing the summary.

13. 59:31
    reasoning 1.3k tok
14. 1:04:35
    Summary425 tok

    Done. The fix is verified end to end; notes on the tradeoffs are in the final message.