* feat: open PRs under user's name and add OpenSWE label
* feat: use user token for PR authorship, add OpenSWE label, and consolidate fallback logic
* linting
* fix: address review nits for PR authorship and labeling
Fix docstring casing, add debug logging for 422 existing-PR search
fallback, tighten test type annotations, and add missing HTTPError
fallback test.
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Co-authored-by: open-swe[bot] <open-swe@users.noreply.github.com>
