When multiple TcpPing requests are sent in parallel for diagnosing
multiple remote addresses, the Go agent was processing them serially.
This caused later requests to timeout (10s) while waiting for earlier
requests to complete.
Changes:
- Only TcpPing commands run in goroutines for parallel execution
- TcpPing (read-only diagnostic) no longer triggers saveConfig()
- Other state-mutating commands remain synchronous with config save
- Add mutex to saveConfig() to protect concurrent file writes
sagit