Join a paged answer, and say one too large instead of timing out (hq issue 314)

An answer larger than the bus's max_payload was refused by the client library
inside its holder, and the caller waited out its 30 s and read silence: the
controller's conditions and status for hours on 2026-10-08. The console now asks
for the parts of an answer the controller paged and joins them; a module's answer
too large for one message is answered as an error saying so, at once.

node-tools/internal/bus/bus.go

@@ -449,7 +449,11 @@ func (c *Conn) answerOn(subject, queue string, h Handler) (func(), error) {
 			}
 			r.Node = c.node
 			body, _ := wire.Marshal(r)
-			_ = msg.Respond(body)
+			// Within what the bus carries, or said to be too large — never a send the library
+			// refuses and the caller waits out (novox/hq issue 314).
+			if err := msg.Respond(c.fits(subject, body)); err != nil {
+				c.Logf("[mesh-tools] could not answer on %s: %v", subject, err)
+			}
 		}()
 	}
 	var sub *nats.Subscription
@@ -614,13 +618,18 @@ func (c *Conn) askOnce(subject string, data []byte) (Answered, bool, error) {
 		}
 		return Answered{}, false, err
 	}
+	// An answer larger than one message comes in parts (pages.go, novox/hq issue 314).
+	body, err := c.whole(subject, msg.Data)
+	if err != nil {
+		return Answered{}, false, err
+	}
 	var r struct {
 		Result json.RawMessage `json:"result"`
 		Error  string          `json:"error"`
 		Node   string          `json:"node"`
 		Retry  string          `json:"retry"`
 	}
-	if err := json.Unmarshal(msg.Data, &r); err != nil {
+	if err := json.Unmarshal(body, &r); err != nil {
 		return Answered{}, false, err
 	}
 	if r.Error != "" {