Update Antique.jl 0.15 API usage

[ohno]

Summary

• update HydrogenAtom and SphericalOscillator keyword arguments to the ASCII names used by Antique.jl 0.15
• replace Antique.E with Antique.energy
• replace Antique.ψ with Antique.wavefunction
• update the same API usage in executable documentation examples

Root cause

Antique.jl 0.15 renamed its public functions and model fields, so the tests and documentation examples no longer compile against the latest release.

Impact

The numerical expectations and tolerances are unchanged. Tests and documentation now use the supported Antique.jl API, allowing the documentation examples to generate their assets successfully.

Validation

• git diff --check passed
• Julia 1.7 tests passed
• Julia 1.10 tests passed
• Documentation build passed
• compared all updated calls with Antique.jl 0.15.0 source and documentation

Agents

This change was assisted by OpenAI Codex GPT-5.6-high:

• creating a Git branch
• updating Antique.jl API usage in tests and documentation
• validating the changes with GitHub Actions
• preparing the pull request

Close #18

[ohno]

Great job, GPT-5.6! 👍