Add jmaplib to the JMAP libraries list

[s-aga-r]

Summary

• Add jmaplib to the Libraries section of the software page. It is a JMAP client library for Python (AGPL-3.0, published on PyPI) with typed models and sync and async APIs.
• It covers JMAP Core (RFC 8620), Mail (RFC 8621), WebSocket (RFC 8887), MDN (RFC 9007), Blob management (RFC 9404), Quotas (RFC 9425), Contacts (RFC 9610), Sieve (RFC 9661) and Sharing (RFC 9670), with push over EventSource, Web Push and WebSocket.
• The entry is placed alphabetically, after jmapc (JMAP compiler) and before melib.

Test plan

• npx prettier --check pages/software.liquid passes.
• The page front matter parses as YAML and the new item sits in the Libraries section.