feat(mockup): add OpenAI Codex (gpt-5.6-sol + built-in image_gen) raster mockup generator

Dockerfile

@@ -6,6 +6,8 @@ ENV NODE_ENV=production
 ENV PORT=80
 ENV DATA_DIR=/app/store
 
+RUN npm install -g @openai/codex@latest
+
 COPY package*.json ./
 RUN npm install --omit=dev