gha/opencode: use gpt-5.2-codex thru zen

Signed-off-by: Sam Day <me@samcday.com>
Assisted-by: gpt-5.1-codex

Author: samcday

.github/workflows/opencode.yml

@@ -28,6 +28,6 @@ jobs:
       - name: Run opencode
         uses: anomalyco/opencode/github@latest
         env:
-          OPENAI_API_KEY: ${{ secrets.OPENAI_API_KEY }}
+          OPENCODE_API_KEY: ${{ secrets.OPENCODE_API_KEY }}
         with:
-          model: openai/gpt-5.1-codex-mini
+          model: opencode/gpt-5.2-codex