ZCode Preview 3.15.1 — ChatGPT OAuth + open-source coding-plan auth

First build of this fork, based on upstream v3.15.1.

What's inside

• Sign in with ChatGPT (Plus/Pro): OpenAI models in the model picker, no API key. One-time login via CLI:
  node "/opt/ZCode Preview/resources/glm/zcode.cjs" login chatgpt
• Coding-plan (GLM) requests from open-source builds go directly to api.z.ai — fixes the 401 that killed every GLM request in self-built apps.
• Subagent retry fix for client signing lifecycle errors.

Install (Debian/Ubuntu) — installs ZCode Preview alongside your regular ZCode, which stays untouched:

sudo apt install ./ZCode-Preview-3.15.1-linux-amd64.deb

The AppImage is also available (chmod +x, then run). See the README for details.