Creates a new BackgroundScan instance.
| tool |
The CodebaseSearchTool instance (provides embedding_client, vector_db, and project_manager.db). |
| git_provider |
The Git provider instance (each thread needs its own instance for thread safety). |
| config |
Config2 instance for Indexer creation. A deep copy is made for thread safety. Changes to config (when preferences dialog closes) will trigger thread restart. |