auth: tolerate settings sync failures after login

[xingyaoww]

Summary

• Treat settings sync API errors as a warning after OAuth instead of failing the post-login data fetch.
• Skip local agent configuration when settings cannot be fetched, while preserving the retrieved LLM key in the returned data.
• Add regression coverage for settings API failures during post-OAuth user data fetch.

Context

Refs #725. This hardens the login flow against settings endpoint failures, but the reproduced local traceback is from the currently published openhands wheel, which still contains the pre-#711 auth client that calls /api/settings and depends on openhands-sdk==1.19.1.

The current main branch already calls /api/v1/settings and depends on openhands-sdk==1.21.0, but the CLI package version remains 1.15.1, so openhands --version alone does not distinguish the stale PyPI wheel from the current checkout.

Tests

• make lint
• make test

[github-actions]

Coverage Report •

File	Stmts	Miss	Cover	Missing
openhands_cli/auth
api_client.py	159	13	91%	44, 138, 174, 221, 230, 245–246, 266, 270, 297, 358–360
TOTAL	6815	967	85%

[github-actions]

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