Small tweaks and cleanup

[bjester]

Summary

• Removes file locking code, instead enforces reconciler only runs in the expected process, and uses thread locking
• Ensures we listen to activity lifecycle events in the main app process, to prevent duplication
• Separates step to load python libraries in worker implementation

[rtibbles]

The changes make sense to me - limiting the life cycle hooks that are only relevant for the worker process, and tweaking where the Python library loading happens all seem sensible to me.

I tested locally on Android 13 in an emulator, and didn't note any regressions in task execution for foreground or background tasks.