SEP-1730: Tier 1 SDK support

[findleyr]

This issue tracks work toward ensuring this SDK conforms with the definition of a Tier 1 SDK in SEP-1730.

Here's where I think we currently stand:

• Feature complete and full support of the protocol
  • All conformance tests pass (document conformance setup; add example client and server #650)
  • New protocol features before the new spec version release. Tracked by 2025-11-25 Implementation (view)
• SDK maintenance
  • Acknowledge and triage issues within two business days
  • Resolve security and critical bugs within seven days
  • Stable release
  • SDK versioning clearly documented (Document SDK version support matrix #674)
• Documentation
  • Comprehensive documentation with examples for all features (see docs)
  • Published dependency update policy (Add a dependency update policy #635)