chore: add spec source comment and upgrade targetFramework in generate.sh

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: HavenDV

src/libs/tryAGI.OpenAI/generate.sh

@@ -1,6 +1,8 @@
 #!/usr/bin/env bash
 set -euo pipefail
 
+# OpenAPI spec: https://app.stainless.com/api/spec/documented/openai/openapi.documented.yml (+ AsyncAPI)
+
 dotnet tool install --global autosdk.cli --prerelease
 curl --fail --silent --show-error -L -o openapi.yaml https://app.stainless.com/api/spec/documented/openai/openapi.documented.yml