[release branch] Correct gpt export param in case export_model.py step is omitted (#3870)

If user skips manual export, the demo fall backs to model conversion via
ovms.exe optimum-cli. In this scenario, it was missing int4 precision

#3868

Author: dkalinowski

demos/continuous_batching/agentic_ai/README.md

@@ -242,7 +242,7 @@ ovms.exe --rest_port 8000 --source_model Qwen/Qwen3-Coder-30B-A3B-Instruct --mod
 :::{tab-item} gpt-oss-20b
 :sync: gpt-oss-20b
 ```bat
-ovms.exe --rest_port 8000 --source_model openai/gpt-oss-20b --model_repository_path models --tool_parser gptoss --reasoning_parser gptoss --target_device GPU --task text_generation --pipeline_type LM
+ovms.exe --rest_port 8000 --source_model openai/gpt-oss-20b --model_repository_path models --tool_parser gptoss --reasoning_parser gptoss --target_device GPU --task text_generation --pipeline_type LM --weight_format int4
 ```
 > **Note:**: Use `--pipeline_type LM` for export and `--target device GPU` for deployment. Expect continuous batching and CPU support in weekly or 2026.0+ releases.
 :::
@@ -475,7 +475,7 @@ docker run -d --user $(id -u):$(id -g) --rm -p 8000:8000 -v $(pwd)/models:/model
 ```bash
 docker run -d --user $(id -u):$(id -g) --rm -p 8000:8000 -v $(pwd)/models:/models --device /dev/dri --group-add=$(stat -c "%g" /dev/dri/render* | head -n 1) openvino/model_server:weekly \
 --rest_port 8000 --source_model openai/gpt-oss-20b --model_repository_path models \
---tool_parser gptoss --reasoning_parser gptoss --target_device GPU --task text_generation --enable_prefix_caching true --pipeline_type LM
+--tool_parser gptoss --reasoning_parser gptoss --target_device GPU --task text_generation --enable_prefix_caching true --pipeline_type LM --weight_format int4
 ```
 > **Note:**: Use `--pipeline_type LM` for export and `--target device GPU` for deployment. Expect continuous batching and CPU support in weekly or 2026.0+ releases.
 :::