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/fit.go

@@ -0,0 +1,95 @@
+// SPDX-License-Identifier: Unlicense OR MIT
+
+package widget
+
+import (
+	"image"
+
+	"gioui.org/f32"
+	"gioui.org/layout"
+)
+
+// Fit scales a widget to fit and clip to the constraints.
+type Fit uint8
+
+const (
+	// Unscaled does not alter the scale of a widget.
+	Unscaled Fit = iota
+	// Contain scales widget as large as possible without cropping
+	// and it preserves aspect-ratio.
+	Contain
+	// Cover scales the widget to cover the constraint area and
+	// preserves aspect-ratio.
+	Cover
+	// ScaleDown scales the widget smaller without cropping,
+	// when it exceeds the constraint area.
+	// It preserves aspect-ratio.
+	ScaleDown
+	// Fill stretches the widget to the constraints and does not
+	// preserve aspect-ratio.
+	Fill
+)
+
+// scale computes the new dimensions and transformation required to fit dims to cs, given the position.
+func (fit Fit) scale(cs layout.Constraints, pos layout.Direction, dims layout.Dimensions) (layout.Dimensions, f32.Affine2D) {
+	widgetSize := dims.Size
+
+	if fit == Unscaled || dims.Size.X == 0 || dims.Size.Y == 0 {
+		dims.Size = cs.Constrain(dims.Size)
+
+		offset := pos.Position(widgetSize, dims.Size)
+		dims.Baseline += offset.Y
+		return dims, f32.AffineId().Offset(layout.FPt(offset))
+	}
+
+	scale := f32.Point{
+		X: float32(cs.Max.X) / float32(dims.Size.X),
+		Y: float32(cs.Max.Y) / float32(dims.Size.Y),
+	}
+
+	switch fit {
+	case Contain:
+		if scale.Y < scale.X {
+			scale.X = scale.Y
+		} else {
+			scale.Y = scale.X
+		}
+	case Cover:
+		if scale.Y > scale.X {
+			scale.X = scale.Y
+		} else {
+			scale.Y = scale.X
+		}
+	case ScaleDown:
+		if scale.Y < scale.X {
+			scale.X = scale.Y
+		} else {
+			scale.Y = scale.X
+		}
+
+		// The widget would need to be scaled up, no change needed.
+		if scale.X >= 1 {
+			dims.Size = cs.Constrain(dims.Size)
+
+			offset := pos.Position(widgetSize, dims.Size)
+			dims.Baseline += offset.Y
+			return dims, f32.AffineId().Offset(layout.FPt(offset))
+		}
+	case Fill:
+	}
+
+	var scaledSize image.Point
+	scaledSize.X = int(float32(widgetSize.X) * scale.X)
+	scaledSize.Y = int(float32(widgetSize.Y) * scale.Y)
+	dims.Size = cs.Constrain(scaledSize)
+	dims.Baseline = int(float32(dims.Baseline) * scale.Y)
+
+	offset := pos.Position(scaledSize, dims.Size)
+	trans := f32.AffineId().
+		Scale(f32.Point{}, scale).
+		Offset(layout.FPt(offset))
+
+	dims.Baseline += offset.Y
+
+	return dims, trans
+}