Fix JSON unmarshal error that occurred when copying channels after testing. The JavaScript timestamp (floating point number) in the test_time field was causing type conversion errors in Go backend which expected an int64.
Solution:
- Create deep copy of channel record instead of modifying original
- Remove test_time and response_time fields before sending to backend
- Allow backend to use default values for these fields
Error fixed: "json: cannot unmarshal number into Go struct field Channel.test_time of type int64"
