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/app/vulkan_x11.go

@@ -0,0 +1,81 @@
+// SPDX-License-Identifier: Unlicense OR MIT
+
+//go:build ((linux && !android) || freebsd) && !nox11 && !novulkan
+// +build linux,!android freebsd
+// +build !nox11
+// +build !novulkan
+
+package app
+
+import (
+	"unsafe"
+
+	"gioui.org/gpu"
+	"gioui.org/internal/vk"
+)
+
+type x11VkContext struct {
+	win  *x11Window
+	inst vk.Instance
+	surf vk.Surface
+	ctx  *vkContext
+}
+
+func init() {
+	newX11VulkanContext = func(w *x11Window) (context, error) {
+		inst, err := vk.CreateInstance("VK_KHR_surface", "VK_KHR_xlib_surface")
+		if err != nil {
+			return nil, err
+		}
+		disp := w.display()
+		window, _, _ := w.window()
+		surf, err := vk.CreateXlibSurface(inst, unsafe.Pointer(disp), uintptr(window))
+		if err != nil {
+			vk.DestroyInstance(inst)
+			return nil, err
+		}
+		ctx, err := newVulkanContext(inst, surf)
+		if err != nil {
+			vk.DestroySurface(inst, surf)
+			vk.DestroyInstance(inst)
+			return nil, err
+		}
+		c := &x11VkContext{
+			win:  w,
+			inst: inst,
+			surf: surf,
+			ctx:  ctx,
+		}
+		return c, nil
+	}
+}
+
+func (c *x11VkContext) RenderTarget() (gpu.RenderTarget, error) {
+	return c.ctx.RenderTarget()
+}
+
+func (c *x11VkContext) API() gpu.API {
+	return c.ctx.api()
+}
+
+func (c *x11VkContext) Release() {
+	c.ctx.release()
+	vk.DestroySurface(c.inst, c.surf)
+	vk.DestroyInstance(c.inst)
+	*c = x11VkContext{}
+}
+
+func (c *x11VkContext) Present() error {
+	return c.ctx.present()
+}
+
+func (c *x11VkContext) Lock() error {
+	return nil
+}
+
+func (c *x11VkContext) Unlock() {}
+
+func (c *x11VkContext) Refresh() error {
+	_, w, h := c.win.window()
+	return c.ctx.refresh(c.surf, w, h)
+}