Fix cannot release un-acquired lock in Blob logger

[gaudyb]

Description

Fixes a crash in BlobWorkflowLogger where base_dir was accepted in init but never stored, causing _rotate_blob to fail on self._base_dir. Also cleans up indentation in _write_log and adds unit test coverage for the logger.

Checklist

• I have tested these changes locally.
• I have reviewed the code changes.
• I have updated the documentation (if necessary).
• I have added appropriate unit tests (if applicable).

[Copilot]

Pull request overview

This PR fixes a crash in BlobWorkflowLogger caused by reinitializing the logging.Handler inside _write_log (leading to “cannot release un-acquired lock”), and also ensures base_dir is stored so blob rotation can reliably build blob names. It adds unit tests to validate initialization, rotation behavior, and log type mapping.

Changes:

• Refactor blob rotation into _rotate_blob() and stop calling self.__init__() during writes.
• Persist base_dir on the logger instance and use it when composing blob paths.
• Add unit tests covering initialization, rotation, append behavior, and level-to-type mapping.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
packages/graphrag/graphrag/logger/blob_workflow_logger.py	Fixes lock crash by avoiding re-init during rotation; stores base_dir; centralizes blob creation in _rotate_blob().
tests/unit/logger/test_blob_workflow_logger.py	Adds tests validating blob initialization, rotation behavior (including lock stability), and log writing/type mapping.
tests/unit/logger/init.py	Adds package marker for the new test module.
.semversioner/next-release/patch-20260717165805703786.json	Records a patch-level release note for the fix.

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