… a sum of nearest-line distances between a theoretical line list and a transformed observed line list.

…with respect to x.

Renamed `wavecal.py` to `lswavecal1d.py` and refactored the `WavelengthSolution1D` class for improved clarity and functionality. Added new methods like `refine_fit`, `pix_to_wav`, and `wav_to_pix`, and modified existing ones to enhance flexibility and maintainability.

Introduce `WavelengthSolution2D` class for 2D wavelength calibration, extending functionality from 1D calibration.

…el and spectral frames.

… type hints, documentation, and method structure. Added new methods for calculating inverse transformations and derivatives. Enhanced plotting functionality with additional parameters and refined docstrings for clarity.

…creduce.

…where `arc_spectra` is `None`.

… `plim` parameter for pixel range control in plotting.

…, and modularity, while resolving associated issues. Enhanced methods for handling pixel-to-wavelength mappings, line-matching processes, and plotting capabilities. Added new functions and properties for better control over data and fit refinement.

…ns with setters to ensure proper masking and validation. Added `plot_lines_pix` and `plot_lines_wav` methods for enhanced modularity in plotting observed and theoretical lines.

…thods, updated property names, and enhanced plotting functionality.

…umentation for plotting and fitting methods.

…ines`.

…e maximum number of iterations for refining the pixel-to-wavelength transformation. This ensures the process adjusts until convergence or the specified iteration limit is reached.

….toml`.

- Added `sphinx-copybutton` and `sphinx-design` to documentation dependencies in `pyproject.toml`.
- Improved content structure by renaming and reorganizing documentation files.
- Expanded "Contributing" and "Index" sections.

…action examples; updated `conf.py` with formatting adjustments and extended Sphinx documentation settings.

- Corrected typos and clarified text.
- Renamed `common.py` to `quickstart.py`.
- Updated function and variable names for consistency.
- Streamlined background subtraction and wavelength calibration workflows.

…uncertainty handling.

…tdDevUncertainty` when absent.

…doc_xref_param_type` configuration.