chore: import upstream snapshot with attribution

pkg/github/ui_embed.go

@@ -0,0 +1,41 @@
+package github
+
+import (
+	"embed"
+)
+
+// UIAssets embeds the built MCP App UI HTML files.
+// These files are generated by running `script/build-ui` which compiles
+// the React/Primer components in the ui/ directory.
+//
+//go:embed ui_dist/*.html
+var UIAssets embed.FS
+
+// GetUIAsset reads a UI asset from the embedded filesystem.
+// The name should be just the filename (e.g., "get-me.html").
+func GetUIAsset(name string) (string, error) {
+	data, err := UIAssets.ReadFile("ui_dist/" + name)
+	if err != nil {
+		return "", err
+	}
+	return string(data), nil
+}
+
+// MustGetUIAsset reads a UI asset and panics if it fails.
+// Use this when the asset is required for server operation.
+func MustGetUIAsset(name string) string {
+	html, err := GetUIAsset(name)
+	if err != nil {
+		panic("failed to load UI asset " + name + ": " + err.Error())
+	}
+	return html
+}
+
+// UIAssetsAvailable returns true if the MCP App UI assets have been built.
+// This checks for a known UI asset file to determine if `script/build-ui` has been run.
+// Use this to gracefully skip UI registration when assets aren't available,
+// allowing non-UI features to work without requiring a UI build.
+func UIAssetsAvailable() bool {
+	_, err := GetUIAsset("get-me.html")
+	return err == nil
+}