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/image.go

@@ -0,0 +1,54 @@
+// SPDX-License-Identifier: Unlicense OR MIT
+
+package widget
+
+import (
+	"image"
+
+	"gioui.org/f32"
+	"gioui.org/layout"
+	"gioui.org/op"
+	"gioui.org/op/clip"
+	"gioui.org/op/paint"
+	"gioui.org/unit"
+)
+
+// Image is a widget that displays an image.
+type Image struct {
+	// Src is the image to display.
+	Src paint.ImageOp
+	// Fit specifies how to scale the image to the constraints.
+	// By default it does not do any scaling.
+	Fit Fit
+	// Position specifies where to position the image within
+	// the constraints.
+	Position layout.Direction
+	// Scale is the factor used for converting image pixels to dp.
+	// If Scale is zero it defaults to 1.
+	//
+	// To map one image pixel to one output pixel, set Scale to 1.0 / gtx.Metric.PxPerDp.
+	Scale float32
+}
+
+func (im Image) Layout(gtx layout.Context) layout.Dimensions {
+	scale := im.Scale
+	if scale == 0 {
+		scale = 1
+	}
+
+	size := im.Src.Size()
+	wf, hf := float32(size.X), float32(size.Y)
+	w, h := gtx.Dp(unit.Dp(wf*scale)), gtx.Dp(unit.Dp(hf*scale))
+
+	dims, trans := im.Fit.scale(gtx.Constraints, im.Position, layout.Dimensions{Size: image.Pt(w, h)})
+	defer clip.Rect{Max: dims.Size}.Push(gtx.Ops).Pop()
+
+	pixelScale := scale * gtx.Metric.PxPerDp
+	trans = trans.Mul(f32.AffineId().Scale(f32.Point{}, f32.Pt(pixelScale, pixelScale)))
+	defer op.Affine(trans).Push(gtx.Ops).Pop()
+
+	im.Src.Add(gtx.Ops)
+	paint.PaintOp{}.Add(gtx.Ops)
+
+	return dims
+}