Update hydrograph - add xarray support, and improve plotting/metrics

[andrevdv]

Directly related to Issue #477 - xarray support

• Added support for xarray.Dataset by converting to a pandas DataFrame internally.
• Added error messages when:
  • only a single discharge series is passed
  • unsupported data formats are used.

Other changes:

Structure

• Moved the hydrograph code out of __init__.py into its own file(hydrograph.py).
• Split the large hydrograph() function into multiple helper functions to reduce complexity and improve maintainability.
• these are all private now, might be worth expanding and making them public at a later stage.

plot:

• Added a grid for improved readability.
• Reference series is always plotted first and drawn on top.
• Reference is visually distinguished when comparing multiple hydrographs.
• Improved default title when no title is provided.

metrics:

• Added metrics_list argument:
  • Allows selecting metrics from the hydrostats package.
  • Defaults to: ["nse", "kge_2009", "sa", "me"].
• Metrics table now includes both abbreviation and full name.

other changes:

• Added selected_year to slice both discharge and precipitation to a single year.
• Added new tests:
  • xarray input
  • single-year slicing
  • multiple discharge series
  • single discharge series
  • error cases

known issues at the moment

• When precipitation is included, the precipitation legend overwrites the discharge legend.
• Long metric names cause the metrics table to automatically reduce font size

possible improvements

• make helper functions public
• Automatically adjust the plot/table height ratio (currently 75/25) based on the number of hydrographs being plotted, improving readability for cases with many or few series.

[andrevdv]

done for the day, do i need to do something with these?

Run codecov/codecov-action@v4
Error: Codecov: Failed to get OIDC token with url: https://codecov.io./ Error message: Unable to get
ACTIONS_ID_TOKEN_REQUEST_URL env variable

if yes, i will work on it tomorrow.