style: Apply gofmt to 37 files

Standardize code formatting across test files and monitor.go.
No functional changes.

internal/hostagent/agent_test.go

@@ -71,4 +71,3 @@ func TestNormalisePlatform(t *testing.T) {
 		})
 	}
 }
-

internal/monitoring/temperature_test.go

@@ -452,7 +452,6 @@ func TestParseRPiTemperature(t *testing.T) {
 	}
 }
 
-
 func TestParseSensorsJSON_PiPartialSensors(t *testing.T) {
 	collector := &TemperatureCollector{}