Remove deprecated GitHub workflows and related files

- Deleted workflows for examples: spider, unsloth, issue comments, PyPI nightly and release, full tests, and CPU tests.
- Cleaned up the migration plan to reflect current status and future tasks.
- Updated LightningAgent to allow optional resourcesId parameter.
- Added ActivityToSpanModelAdapter for converting Activity instances to SpanModel records.
- Implemented unit tests for ActivityToSpanModelAdapter to ensure correct functionality.

Author: KSemenenko