Enhance examples

[konstntokas]

• Fixed an issue in xr.open_dataset (native mode) where selecting variables did not
  drop unused coordinates; these are now removed correctly.
• Corrected the data type of the Sentinel-2 Level-2A SCL data array in analysis mode
  (now uint8 instead of float64). The underlying issue has been reported to the
  CPM repository: https://gitlab.eopf.copernicus.eu/cpm/eopf-cpm/-/issues/1044
• Added improved example notebooks to the documentation.
• Fixed issues in integration tests.
• Updated Zarr dependency to require zarr>=3.0.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

Files with missing lines	Coverage Δ
xarray_eopf/amodes/sentinel2.py	100.00% <100.00%> (ø)
xarray_eopf/filter.py	100.00% <100.00%> (ø)
xarray_eopf/source.py	100.00% <100.00%> (ø)
xarray_eopf/version.py	100.00% <100.00%> (ø)

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