fix: 修复语音停顿导致提前粘贴的问题（累积文本，松开按钮才粘贴）

internal/asr/client.go

@@ -74,7 +74,7 @@ func Dial(cfg Config, resultCh chan<- wsMsg.ServerMsg) (*Client, error) {
 			EnableDDC:      true,
 			ShowUtterances: false,
 			ResultType:     "single",
-			EndWindowSize:  400,
+			EndWindowSize:  2000,
 		},
 	}
 	data, err := EncodeFullClientRequest(req)
@@ -132,10 +132,15 @@ func (c *Client) readLoop(resultCh chan<- wsMsg.ServerMsg) {
 			resultCh <- wsMsg.ServerMsg{Type: wsMsg.MsgError, Message: resp.ErrMsg}
 			return
 		}
-		// nostream mode: result comes after last audio packet or >15s
+		// nostream mode: may return intermediate results every ~15s
 		text := resp.Text
 		if text != "" {
-			resultCh <- wsMsg.ServerMsg{Type: wsMsg.MsgFinal, Text: text}
+			if resp.IsLast {
+				resultCh <- wsMsg.ServerMsg{Type: wsMsg.MsgFinal, Text: text}
+			} else {
+				// Intermediate result (>15s audio) — preview only, don't paste
+				resultCh <- wsMsg.ServerMsg{Type: wsMsg.MsgPartial, Text: text}
+			}
 		}
 		if resp.IsLast {
 			return