v0.2.2

Changes

• Docs: README gains a Sponsors section (Enki Multimedia logo vendored under docs/images/).
• Docs: fix invalid webtransport:open_stream(Session, bidi | uni) snippet — type-union pipe was in expression position; now bidi %% or uni.
• CT: cover listeners/0, listener_info/1, and start_listener/2 cert/key error paths (webtransport.erl line coverage 51% → 54%).

See CHANGELOG.md for the full history.