fix: resolve type checking errors

[ArkVex]

Description

This PR implements the logic to calculate and populate the ingested_forecast_length coordinate for the GFS dataset, as requested in #412.

This metric helps downstream users determine the maximum available lead time for each initialization time, allowing them to filter for "complete" forecasts.

Changes

1. Shared Utility: Created src/reformatters/common/ingest_stats.py with a new function update_ingested_forecast_length.
   • Defined a HasTimeInfo Protocol to ensure type safety when processing coordinates.
   • Logic identifies the maximum lead time per init_time and updates the dataset in place.
2. GFS Integration: Updated src/reformatters/noaa/gfs/region_job.py.
   • Overrode update_template_with_results to call the new utility after the standard update process.
3. Testing: Added unit tests in tests/common/test_ingest_stats.py to verify:
   • Correct calculation of max lead times.
   • Proper handling of updates (overwriting smaller values with larger ones).
   • Handling of pd.NaT and empty states.

Testing

• Added new unit tests: tests/common/test_ingest_stats.py.
• Verified type checking passes with ty (using type: ignore for specific pandas timedelta edge cases).

Related Issue

Closes #412

CC @aldenks @JackKelly