CI failure: test_readers_in_pre_init_dir asserted no Traceback in stderr
when running `agnes snapshot create x --as y --estimate` in a folder
that never saw `agnes init`. The estimate-guard fix in 3d587681 let
`--estimate` skip the local_db check and reach `api_post_json`, but the
existing `except V2ClientError` doesn't cover transport-layer failures.
With no server configured the URL defaults to http://localhost:8000;
httpx raises ConnectError → ConnectError isn't a V2ClientError → the
exception bubbles up through Typer/rich as a full traceback.
Add `except httpx.HTTPError` next to V2ClientError so connection /
DNS / TLS / timeout failures all render the friendly hint
`Run `agnes init …` first` instead of leaking transport noise.
e323ab76cc