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/f32/f32.go

@@ -0,0 +1,60 @@
+// SPDX-License-Identifier: Unlicense OR MIT
+
+/*
+Package f32 is a float32 implementation of package image's
+Point and affine transformations.
+
+The coordinate space has the origin in the top left
+corner with the axes extending right and down.
+*/
+package f32
+
+import (
+	"image"
+	"math"
+	"strconv"
+)
+
+// A Point is a two dimensional point.
+type Point struct {
+	X, Y float32
+}
+
+// String return a string representation of p.
+func (p Point) String() string {
+	return "(" + strconv.FormatFloat(float64(p.X), 'f', -1, 32) +
+		"," + strconv.FormatFloat(float64(p.Y), 'f', -1, 32) + ")"
+}
+
+// Pt is shorthand for Point{X: x, Y: y}.
+func Pt(x, y float32) Point {
+	return Point{X: x, Y: y}
+}
+
+// Add return the point p+p2.
+func (p Point) Add(p2 Point) Point {
+	return Point{X: p.X + p2.X, Y: p.Y + p2.Y}
+}
+
+// Sub returns the vector p-p2.
+func (p Point) Sub(p2 Point) Point {
+	return Point{X: p.X - p2.X, Y: p.Y - p2.Y}
+}
+
+// Mul returns p scaled by s.
+func (p Point) Mul(s float32) Point {
+	return Point{X: p.X * s, Y: p.Y * s}
+}
+
+// Div returns the vector p/s.
+func (p Point) Div(s float32) Point {
+	return Point{X: p.X / s, Y: p.Y / s}
+}
+
+// Round returns the integer point closest to p.
+func (p Point) Round() image.Point {
+	return image.Point{
+		X: int(math.Round(float64(p.X))),
+		Y: int(math.Round(float64(p.Y))),
+	}
+}