gstack Workflows

A ChatGPT and Codex adaptation of the gstack engineering workflows. It keeps the familiar specialist jobs for product planning, architecture review, debugging, code review, QA, design, security, documentation, release work, browser tasks, and iOS workflows while mapping execution to capabilities actually available on the current host. Native gstack browser, device, pairing, gbrain, and local-runtime behavior remains optional and is used only on compatible Codex hosts.