Add discoverable chain pattern and cross-border trade use cases

[onthebreeze]

Summary

• Adds a "Recognition Patterns" subsection to the Introduction describing two patterns: the pre-configured list pattern and the discoverable chain pattern (where recognition credentials are discovered via DID service endpoints and verified by matching issuer/subject DIDs along a chain)
• Adds two new use cases under "Discoverable Chain Use Cases":
  • Streamlined Border Clearance for Cross-Border Trade — customs authority verifies a commercial invoice by following the chain from exporter to national business register to UN GRID
  • Verifiable Product Conformity — buyer/regulator verifies a conformity certificate by following the chain from auditor to national accreditation authority to GACI
• Adds sample JSON files in list-example/ illustrating both chains (recognized entity credentials and DID documents with service endpoints)
• Updates "Commonalities and Differences" to acknowledge the discoverable chain pattern

Addresses #66

Test plan

• Review rendered use-cases.html via PR preview
• Verify JSON examples are valid and entity names are consistent across use case text and sample files
• Verify DID subject/issuer linkage is correct across the chain examples

🤖 Generated with Claude Code

[iherman]

Regardless of whether this PR is acceptable or not, it looks like it is non-substantial, ie, it does not contain recommendation-track material. If that is indeed the case, I can release the IPR lock. Is that correct? Should I remove the lock?

@msporny ?

[msporny]

Regardless of whether this PR is acceptable or not, it looks like it is non-substantial, ie, it does not contain recommendation-track material. If that is indeed the case, I can release the IPR lock. Is that correct? Should I remove the lock?

My presumption is that @onthebreeze is going to make more contributions and we need to get his Github account fixed up, if not now, it'll need to happen in the next PR. Let's just get it sorted now (don't release the lock, @iherman)... shouldn't take more than a day or so to get it fixed up.

[onthebreeze]

All good - I think I'm connected up now.