prolate/oblate spheroidal angular- and radial functions

[jorenham]

• prolate_aswfa[_nocv]
• oblate_aswfa[_nocv]
• prolate_radial1[_nocv]
• oblate_radial1[_nocv]
• prolate_radial2[_nocv]
• oblate_radial2[_nocv]

[Copilot]

Pull Request Overview

This PR adds support for prolate and oblate spheroidal angular and radial functions by implementing 12 new functions in the spheroidal wave module. These functions compute spheroidal functions of the first and second kinds along with their derivatives, with variants that either compute characteristic values internally or accept pre-computed ones.

• Implements 6 _nocv variant functions that compute characteristic values internally
• Implements 6 functions that accept pre-computed characteristic values for better performance
• Adds comprehensive test coverage for all new functions using the existing test framework

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
src/sphd_wave.rs	Implements 12 new spheroidal function wrappers with full documentation
src/lib.rs	Exports all new functions from the sphd_wave module
build.rs	Adds function type signatures for binding generation
tests/test_functions.rs	Adds test macros and test cases for all new functions

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