tag v3.9.0: hub.sr.ht project writes and discovery

The hub.sr.ht GraphQL API gained project mutations and a public projects
query, so Hutch's projects went read-write: create (#13), edit (#14), and
manage linked repositories, trackers, and mailing lists (#15), plus a
Discover browser for public projects (#12). Built against the master schema;
live deployment on sr.ht/query still wants on-device confirmation.

Also in this release:
- Multi-language syntax highlighting via Highlightr, in the file viewer and
  in README / ticket / comment code blocks (#16).
- App Intents expansion: Check Status / Check Builds now speak their result,
  Search Hutch takes a search type, and Clear Recent Activity / Unpin
  Resource are mutating intents (#17).
- Man-page catalog synced from man.sr.ht by a scheduled workflow (#7).
- Fixes: inline-code checklist rendering (#18), clear recent activity (#11),
  and inbox unread count off the pull-to-refresh critical path (#9).