feat(examples): add biomedical healthcare research use case

[ognome-dev]

Summary

This PR adds a biomedical healthcare research example to the examples/ directory, demonstrating how to publish a schema.org/MedicalStudy knowledge asset to the DKG with full PubMed citation provenance.

Use Case

Healthcare and biomedical platforms can use the DKG to publish AI-generated research reports as verifiable, queryable knowledge assets. Each asset carries:

• Structured diagnosis data (MedicalStudy + MedicalCondition)
• PubMed citations as ScholarlyArticle references (source provenance)
• Custom vocabulary for confidence scores and herb/supplement evidence (og: prefix)
• A link back to the corresponding on-chain NFT (Solana mint address)

This pattern enables cross-platform SPARQL queries over biomedical knowledge anchored on the DKG.

What Changed

• Added examples/biomedical-research.js

The example follows the same structure as the existing demo.js and paranet-demo.js files: ES module imports, BLOCKCHAIN_IDS constants, dotenv/config, and the divider() logging pattern.

Schema Preview

{
  "@context": {
    "@vocab": "https://schema.org/",
    "og": "https://opengenome.bio/schema/v1/"
  },
  "@type": "MedicalStudy",
  "studySubject": { "@type": "MedicalCondition", "name": "Hantavirus Pulmonary Syndrome" },
  "citation": [{ "@type": "ScholarlyArticle", "identifier": "PMID:21945235" }]
}

Testing

Tested on Base Sepolia testnet (base:84532) with TRAC from the OriginTrail faucet.

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Happy to adjust the schema namespace or example structure based on any feedback from the maintainers.