dev-mode OAuth callback ignores TANGLED_APPVIEW_HOST #684

In dev mode the OAuth client URI is hardcoded

TANGLED_APPVIEW_HOST is respected everywhere else, so if host port 3000 is taken you can remap the appview port in the compose setup, but login breaks: the PDS redirects the OAuth callback to whatever is using on 3000.

ran into this while fixing https://tangled.org/tangled.org/core/issues/683