Ships the stdlib egress transport (#124): client() falls back to an
http.client + ssl implementation over the broker socket when neither httpx2
nor httpx is in the closure, which is the case in every frozen/offline agent
bundle. Precedence stays httpx2 > httpx > stdlib, so installs that already
work are unaffected.

Carries exactly one commit over python-v0.1.11, plus the version bump.