chore(v2): vendor dependencies for offline/China builds

go mod vendor pins onnxruntime_go v1.12.1, Gio and the rest into v2/vendor
so go run/build work without hitting proxy.golang.org (blocked/slow in
China). Verified: CGO_ENABLED=1 go build -mod=vendor ./internal/spike and
GOOS=windows go build -mod=vendor ./internal/ui both pass.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

v2/vendor/gioui.org/widget/float.go

@@ -0,0 +1,71 @@
+// SPDX-License-Identifier: Unlicense OR MIT
+
+package widget
+
+import (
+	"image"
+
+	"gioui.org/gesture"
+	"gioui.org/io/pointer"
+	"gioui.org/layout"
+	"gioui.org/op/clip"
+	"gioui.org/unit"
+)
+
+// Float is for selecting a value in a range.
+type Float struct {
+	// Value is the value of the Float, in the [0; 1] range.
+	Value float32
+
+	drag   gesture.Drag
+	axis   layout.Axis
+	length float32
+}
+
+// Dragging returns whether the value is being interacted with.
+func (f *Float) Dragging() bool { return f.drag.Dragging() }
+
+func (f *Float) Layout(gtx layout.Context, axis layout.Axis, pointerMargin unit.Dp) layout.Dimensions {
+	f.Update(gtx)
+	size := gtx.Constraints.Min
+	f.length = float32(axis.Convert(size).X)
+	f.axis = axis
+
+	margin := axis.Convert(image.Pt(gtx.Dp(pointerMargin), 0))
+	rect := image.Rectangle{
+		Min: margin.Mul(-1),
+		Max: size.Add(margin),
+	}
+	defer clip.Rect(rect).Push(gtx.Ops).Pop()
+	f.drag.Add(gtx.Ops)
+
+	return layout.Dimensions{Size: size}
+}
+
+// Update the Value according to drag events along the f's main axis.
+// The return value reports whether the value was changed.
+//
+// The range of f is set by the minimum constraints main axis value.
+func (f *Float) Update(gtx layout.Context) bool {
+	changed := false
+	for {
+		e, ok := f.drag.Update(gtx.Metric, gtx.Source, gesture.Axis(f.axis))
+		if !ok {
+			break
+		}
+		if f.length > 0 && (e.Kind == pointer.Press || e.Kind == pointer.Drag) {
+			pos := e.Position.X
+			if f.axis == layout.Vertical {
+				pos = f.length - e.Position.Y
+			}
+			f.Value = pos / f.length
+			if f.Value < 0 {
+				f.Value = 0
+			} else if f.Value > 1 {
+				f.Value = 1
+			}
+			changed = true
+		}
+	}
+	return changed
+}