feat: add transplanted 1D quadrature maps, docs, tests

[xywei]

Summary

This PR adds transplanted 1D quadrature support to modepy using Hale–Trefethen/Kosloff–Tal-Ezer style maps, with docs and tests.

• Add new module: modepy/quadrature/transplanted.py
  • map functions:
    • map_identity
    • map_sausage
    • map_kosloff_tal_ezer (kte / kosloff_tal_ezer)
    • map_strip
  • dispatcher:
    • map_trefethen_transplant
  • quadrature wrappers:
    • transplanted_1d_quadrature
    • transplanted_legendre_gauss_quadrature
• Export wrappers at top level from modepy.__init__.
• Add dedicated transplanted quadrature docs in doc/quadrature.rst with map-specific guidance and references.
• Add transplanted-focused tests in modepy/test/test_quadrature.py (map consistency, strip endpoint rejection, KTE validation, sausage degree checks).

What for

These quadrature rules are good at integrating QBX coefficients:

API Notes

• Canonical sausage API is now:
  • map_name="sausage" with sausage_degree=<odd int>
• Backward-compatible map-name alias is still accepted in dispatcher:
  • map_name="sausage_d{odd}"
• Public API for this feature is function/wrapper-based (no Transplanted* class API introduced).
• exact_to is preserved for identity-preserving mappings (identity and sausage degree 1), and unset otherwise.

Documentation Updates

• Added a dedicated transplanted section anchor in docs.
• Clarified transformed-weight notation (w_i^{(s)} vs mapped weights).
• Improved citation formatting (italic journal names + clickable DOI links).
• Reduced duplicated reference text between module docstrings and doc/quadrature.rst.

Validation

• ruff check
• basedpyright
• pytest modepy/test/test_quadrature.py -k transplanted
• Full CI on PR (including docs and downstream jobs)

[inducer]

Thanks! Could you look at those linter failures? The biggest one is probably adding types.

[inducer]

(I can help if there's an issue.)

[inducer]

cc @ShawnL00

[Copilot]

Pull request overview

Adds transplanted 1D quadrature rules/maps (Hale–Trefethen and Kosloff–Tal-Ezer) to modepy, with accompanying docs, tests, and a QBX comparison example.

Changes:

• Introduces modepy.quadrature.transplanted with transplant maps, a dispatcher, and transplanted quadrature classes.
• Exports transplanted quadrature classes through package init modules (modepy.quadrature and top-level modepy).
• Adds docs + tests for map dispatch/validation and includes a 2D QBX comparison example script.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
modepy/quadrature/transplanted.py	New transplanted-map implementations and transplanted quadrature classes.
modepy/quadrature/__init__.py	Re-exports transplanted quadrature classes from the quadrature package.
modepy/__init__.py	Exposes transplanted quadrature classes at the top-level modepy API.
modepy/test/test_quadrature.py	Adds unit tests for transplanted quadrature mapping/validation behavior.
examples/plot-qbx-transplanted-vs-gauss.py	New QBX comparison example for Gauss vs transplanted rules.
doc/quadrature.rst	Adds documentation section describing transplanted quadrature usage and references.

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[Copilot]

The example writes output to a hard-coded /tmp/... path, which will fail on non-POSIX platforms (e.g. Windows) and can be surprising for users.

Consider using tempfile.gettempdir()/pathlib.Path, saving relative to the current working directory, or making the output path a CLI argument.

[alexfikl]

Very nifty! 😁

I took a quick look and left some nitpicks and questions.

[inducer]

Thanks for making this! Pretty close, just a few small wrinkles.

[inducer]

I've addressed the review feedback. LGTM now. @alexfikl?

[alexfikl]

Left a bunch of nitpicks in the docs and the example, but otherwise looks good to me too 😁