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/gpu/internal/opengl/srgb.go

@@ -0,0 +1,176 @@
+// SPDX-License-Identifier: Unlicense OR MIT
+
+package opengl
+
+import (
+	"errors"
+	"fmt"
+	"image"
+	"runtime"
+	"strings"
+
+	"gioui.org/internal/byteslice"
+	"gioui.org/internal/gl"
+)
+
+// SRGBFBO implements an intermediate sRGB FBO
+// for gamma-correct rendering on platforms without
+// sRGB enabled native framebuffers.
+type SRGBFBO struct {
+	c        *gl.Functions
+	state    *glState
+	viewport image.Point
+	fbo      gl.Framebuffer
+	tex      gl.Texture
+	blitted  bool
+	quad     gl.Buffer
+	prog     gl.Program
+	format   textureTriple
+}
+
+func NewSRGBFBO(f *gl.Functions, state *glState) (*SRGBFBO, error) {
+	glVer := f.GetString(gl.VERSION)
+	ver, _, err := gl.ParseGLVersion(glVer)
+	if err != nil {
+		return nil, err
+	}
+	exts := strings.Split(f.GetString(gl.EXTENSIONS), " ")
+	srgbTriple, err := srgbaTripleFor(ver, exts)
+	if err != nil {
+		// Fall back to the linear RGB colorspace, at the cost of color precision loss.
+		srgbTriple = textureTriple{gl.RGBA, gl.Enum(gl.RGBA), gl.Enum(gl.UNSIGNED_BYTE)}
+	}
+	s := &SRGBFBO{
+		c:      f,
+		state:  state,
+		format: srgbTriple,
+		fbo:    f.CreateFramebuffer(),
+		tex:    f.CreateTexture(),
+	}
+	state.bindTexture(f, 0, s.tex)
+	f.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE)
+	f.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE)
+	f.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST)
+	f.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST)
+	return s, nil
+}
+
+func (s *SRGBFBO) Blit() {
+	if !s.blitted {
+		prog, err := gl.CreateProgram(s.c, blitVSrc, blitFSrc, []string{"pos", "uv"})
+		if err != nil {
+			panic(err)
+		}
+		s.prog = prog
+		s.state.useProgram(s.c, prog)
+		s.c.Uniform1i(s.c.GetUniformLocation(prog, "tex"), 0)
+		s.quad = s.c.CreateBuffer()
+		s.state.bindBuffer(s.c, gl.ARRAY_BUFFER, s.quad)
+		coords := byteslice.Slice([]float32{
+			-1, +1, 0, 1,
+			+1, +1, 1, 1,
+			-1, -1, 0, 0,
+			+1, -1, 1, 0,
+		})
+		s.c.BufferData(gl.ARRAY_BUFFER, len(coords), gl.STATIC_DRAW, coords)
+		s.blitted = true
+	}
+	s.state.useProgram(s.c, s.prog)
+	s.state.bindTexture(s.c, 0, s.tex)
+	s.state.vertexAttribPointer(s.c, s.quad, 0 /* pos */, 2, gl.FLOAT, false, 4*4, 0)
+	s.state.vertexAttribPointer(s.c, s.quad, 1 /* uv */, 2, gl.FLOAT, false, 4*4, 4*2)
+	s.state.setVertexAttribArray(s.c, 0, true)
+	s.state.setVertexAttribArray(s.c, 1, true)
+	s.c.DrawArrays(gl.TRIANGLE_STRIP, 0, 4)
+	s.state.bindFramebuffer(s.c, gl.FRAMEBUFFER, s.fbo)
+	s.c.InvalidateFramebuffer(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0)
+}
+
+func (s *SRGBFBO) Framebuffer() gl.Framebuffer {
+	return s.fbo
+}
+
+func (s *SRGBFBO) Refresh(viewport image.Point) error {
+	if viewport.X == 0 || viewport.Y == 0 {
+		return errors.New("srgb: zero-sized framebuffer")
+	}
+	if s.viewport == viewport {
+		return nil
+	}
+	s.viewport = viewport
+	s.state.bindTexture(s.c, 0, s.tex)
+	s.c.TexImage2D(gl.TEXTURE_2D, 0, s.format.internalFormat, viewport.X, viewport.Y, s.format.format, s.format.typ)
+	s.state.bindFramebuffer(s.c, gl.FRAMEBUFFER, s.fbo)
+	s.c.FramebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, s.tex, 0)
+	if st := s.c.CheckFramebufferStatus(gl.FRAMEBUFFER); st != gl.FRAMEBUFFER_COMPLETE {
+		return fmt.Errorf("sRGB framebuffer incomplete (%dx%d), status: %#x error: %x", viewport.X, viewport.Y, st, s.c.GetError())
+	}
+
+	if runtime.GOOS == "js" {
+		// With macOS Safari, rendering to and then reading from a SRGB8_ALPHA8
+		// texture result in twice gamma corrected colors. Using a plain RGBA
+		// texture seems to work.
+		s.state.setClearColor(s.c, .5, .5, .5, 1.0)
+		s.c.Clear(gl.COLOR_BUFFER_BIT)
+		var pixel [4]byte
+		s.c.ReadPixels(0, 0, 1, 1, gl.RGBA, gl.UNSIGNED_BYTE, pixel[:])
+		if pixel[0] == 128 { // Correct sRGB color value is ~188
+			s.c.TexImage2D(gl.TEXTURE_2D, 0, gl.RGBA, viewport.X, viewport.Y, gl.RGBA, gl.UNSIGNED_BYTE)
+			if st := s.c.CheckFramebufferStatus(gl.FRAMEBUFFER); st != gl.FRAMEBUFFER_COMPLETE {
+				return fmt.Errorf("fallback RGBA framebuffer incomplete (%dx%d), status: %#x error: %x", viewport.X, viewport.Y, st, s.c.GetError())
+			}
+		}
+	}
+
+	return nil
+}
+
+func (s *SRGBFBO) Release() {
+	s.state.deleteFramebuffer(s.c, s.fbo)
+	s.state.deleteTexture(s.c, s.tex)
+	if s.blitted {
+		s.state.deleteBuffer(s.c, s.quad)
+		s.state.deleteProgram(s.c, s.prog)
+	}
+	s.c = nil
+}
+
+const (
+	blitVSrc = `
+#version 100
+
+precision highp float;
+
+attribute vec2 pos;
+attribute vec2 uv;
+
+varying vec2 vUV;
+
+void main() {
+    gl_Position = vec4(pos, 0, 1);
+    vUV = uv;
+}
+`
+	blitFSrc = `
+#version 100
+
+precision mediump float;
+
+uniform sampler2D tex;
+varying vec2 vUV;
+
+vec3 gamma(vec3 rgb) {
+	vec3 exp = vec3(1.055)*pow(rgb, vec3(0.41666)) - vec3(0.055);
+	vec3 lin = rgb * vec3(12.92);
+	bvec3 cut = lessThan(rgb, vec3(0.0031308));
+	return vec3(cut.r ? lin.r : exp.r, cut.g ? lin.g : exp.g, cut.b ? lin.b : exp.b);
+}
+
+void main() {
+    vec4 col = texture2D(tex, vUV);
+	vec3 rgb = col.rgb;
+	rgb = gamma(rgb);
+	gl_FragColor = vec4(rgb, col.a);
+}
+`
+)