Add citation metadata and archival release preparation

[dcajal]

Goal

Prepare Biosiglib for software citation and archival release.

Required files

Add at least:

CITATION.cff
.zenodo.json

Optional later:

codemeta.json

CITATION.cff

The file should describe Biosiglib as research software / software infrastructure, not as a scientific algorithm paper.

It should include:

• Project title.
• Current version.
• Release date.
• Repository URL.
• Software authors/contributors.
• Message instructing users how to cite Biosiglib.
• Preferred citation placeholder if a JOSS/SoftwareX paper is later accepted.

Do not invent ORCIDs or affiliations. Use placeholders or omit fields when unknown.

Zenodo metadata

Add .zenodo.json with:

• title
• creators
• description
• license
• keywords
• related identifiers where appropriate

Do not include a DOI until Zenodo has minted one.

README updates

Add a short citation section explaining:

• how to cite the software release;
• that scientific algorithm publications must still be cited separately;
• that the software citation and scientific method citations are complementary.

Validation

• Validate CITATION.cff if local tooling is available.
• Validate .zenodo.json is valid JSON.
• Run existing Biosiglib validation:
  • python tools/validate_specs.py
  • python -m compileall tools
• Run git diff --check.

Notes

This issue is about citation metadata only. It should not create a real Zenodo deposit and should not create a new Biosiglib release.