Add an e2e suite mocking the capability probe, the chat history GET, and the
streaming chat POST so the panel renders (v1.27.31 lesson): the entry opens an
empty safety-noted surface, a turn streams a reply that settles to one assistant
bubble, a non-indexed document shows the calm hint, and no provider leaves no
chat surface. Clear the streamed tail + optimistic bubble once the persisted
twin lands so the reply never double-renders.
Marc-André Bombeck