phraser, mavend: read the fallbacks from the file (V-501)

The accessors are functions now, so the call sites that compared against one
literal compare against the entry instead: IsUnknownFallback and
IsSourcesFallback in the daemon tests, the entry key in the phraser tests. A
reworded variant no longer breaks a Go test.

The eval scores every variant on the persona checks the nudges already pass.

cmd/mavend/actions_query.go

@@ -798,7 +798,7 @@ func (h *reactiveHandler) queryGeneral(ctx context.Context, t *queryTurn) (strin
 	reply, err := h.phraseWorld(ctx, t.dec.Utterance, nil)
 	if errors.Is(err, phraser.ErrNoWorldModel) {
 		log.Printf("voice: %q needs the world model and it is not available", t.dec.Utterance)
-		return worldGap, true
+		return worldGap(), true
 	}
 	if err != nil || reply == "" {
 		return "не знаю.", true