feat: add container shell + skills support

[seratch]

This pull request adds hosted shell runtime tool along with its native skills support. Developers now can pass a container-based shell runtime with skills this way:

from agents import Agent, ShellTool

agent = Agent(
    name="Shell Agent",
    model="gpt-5.2",
    instructions="Use the available shell tool to answer user requests.",
    tools=[
        ShellTool(
            environment={
                "type": "container_auto",
                "network_policy": {"type": "disabled"},
                "skills": [
                    {
                        "type": "skill_reference",
                        "skill_id": "skill_698bbe879adc81918725cbc69dcae7960bc5613dadaed377",
                        "version": "1",
                    }
                ],
            }
        )
    ],
)

Refer to examples/tools/container_shell_inline_skill.py and examples/tools/container_shell_skill_reference.py for more details.

references:

• Hosted shell: https://developers.openai.com/api/docs/guides/tools-shell#hosted-runtime-details
• Skills API: https://developers.openai.com/api/docs/guides/tools-skills
• Skills Cookbook: https://developers.openai.com/cookbook/examples/skills_in_api

[chatgpt-codex-connector]

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