v0.9.1 — Bug fixes + tutorial repair

0.9.1 — Bug fixes + tutorial repair

Fixes

• PDSReader now handles OBJECT = SPECTRUM PDS3 labels (29 such files
  exist in the UVIS archive — single-integration interplanetary H/He scans
  like EUV2004_018_10_08). SPECTRUM data is surfaced as a degenerate
  (binned_bands, 1, 1) 3-D array so callers can keep treating
  PDSReader.data as 3-D regardless of object type.
• PDSReader accepts str paths again (previously crashed with
  AttributeError: 'str' object has no attribute 'with_suffix').
• Unsupported PDS object types (e.g. TIME_SERIES) now raise a clear
  ValueError naming the supported types and pointing to issue #10.
• pyuvis.calib.greg.get_star_obs() now loads its bundled stars_list.txt
  via importlib.resources instead of a hardcoded Linux path; the file
  ships inside the package (src/pyuvis/calib/stars_list.txt).

Documentation

• Repaired the Quarto tutorial notebooks under docs/tutorials/ after the
  v0.9.0 nbdev-strip removed their imports. Each tutorial now has an
  explicit Setup cell with the imports it needs; data-fetch demo cells
  are marked #| eval: false so the docs site renders cleanly without
  PDS data on the runner.
• Dropped 08_stats.ipynb from the sidebar (single orphan cell with no
  recoverable content; file kept on disk for later revival).

Tests

• Added tests/test_pdsreader.py covering the QUBE and SPECTRUM code
  paths plus the unsupported-type error path. Network tests are gated
  behind @pytest.mark.network and skipped by default; opt in with
  pytest -m network.