Feat/llm page tracking

[raymondcen]

• Updated the metric extraction process in local_llm.py to:

  • Store the original extracted text for later reference.
  • Add a new field source_pages to the output metrics, listing all pages where metric values were found.

• Updated imports in local_llm.py to include re and adjust type hints for new logic.

• Updated documentation in extract_metrics_from_text to note the presence of page markers in the input text.