feat(observability-lib): add AxisSoftMin and AxisSoftMax options

Add support for configurable soft min/max axis values in time series
panels. Soft limits suggest axis bounds while allowing data outside
the range to remain visible, improving visualization consistency
across dashboards.

Author: leeyikjiun

observability-lib/grafana/panels.go

@@ -326,6 +326,8 @@ type TimeSeriesPanelOptions struct {
 	ThresholdStyle    common.GraphThresholdsStyleMode
 	DrawStyle         common.GraphDrawStyle
 	StackingMode      common.StackingMode
+	AxisSoftMin       *float64
+	AxisSoftMax       *float64
 }
 
 func NewTimeSeriesPanel(options *TimeSeriesPanelOptions) *Panel {
@@ -392,6 +394,14 @@ func NewTimeSeriesPanel(options *TimeSeriesPanelOptions) *Panel {
 		newPanel.Max(*options.Max)
 	}
 
+	if options.AxisSoftMin != nil {
+		newPanel.AxisSoftMin(*options.AxisSoftMin)
+	}
+
+	if options.AxisSoftMax != nil {
+		newPanel.AxisSoftMax(*options.AxisSoftMax)
+	}
+
 	for _, q := range options.Query {
 		newPanel.WithTarget(newQuery(q))
 	}