pending-state-makes-waiting-legible

Model "asked, and not yet answered" as its own field, because without it a rejected request and a peer who simply has not looked at their screen are indistinguishable — both look like nothing happened. Covers the one set against many clears, clearing locally when no answer will ever come, and giving the user a way out. Use when an action appears to do nothing, when a screen can get stuck waiting forever, or when an…