Interface, conversation and repository each speak their own language

Obeya's interface language now covers only Obeya's own words, so switching it to test the other language no longer switches the agents with it. Agents answer in the language you last wrote or spoke to them in, a task you wrote yourself included, and otherwise in a conversation language of your choosing. What lands in git follows a language each repository sets, English by default, so a German conversation still produces English code, commit messages and docs.