fix(server): make openai an optional server-only dependency

[Pouyanpi]

Description

Resolves some minor issues due to #1340 ‪that causes a job failure.

• Mark openai as an optional dependency in pyproject.toml (already included in the server extras group)
• Install wheel with [server] extra in the CI test-wheel job since it starts a server
• Guard the server import in the CLI with a helpful error message when openai is missing
• Add openai to dev dependencies so server tests pass locally (consistent with yara-python, opentelemetry-api, etc.)
• Add pytest.importorskip("openai") guards to all server test files as a defensive measure

[greptile-apps]

Greptile Overview

Greptile Summary

This PR makes openai an optional dependency that's only required when running the guardrails server. The change consists of:

• Marking openai as optional in pyproject.toml (it's already included in the server extras group)
• Adding graceful ImportError handling in the CLI's server command with a clear error message guiding users to install nemoguardrails[server]
• Updating the CI workflow to install the wheel with [server] extra since the test-wheel job starts a server
• Poetry automatically updated poetry.lock to mark transitive dependencies (distro, jiter) as optional

This improves the user experience by allowing users to install a lighter version of the package when they don't need server functionality, while providing clear guidance when the server dependencies are missing.

Confidence Score: 5/5

• This PR is safe to merge with minimal risk
• All changes are well-coordinated: the dependency is properly marked as optional, the CLI provides helpful error handling, and the CI is updated to accommodate the change. The implementation follows best practices for optional dependencies and provides a good user experience.
• No files require special attention

Important Files Changed

Filename	Overview
pyproject.toml	Correctly marks openai as optional dependency, already included in server extras group
poetry.lock	Transitive dependencies (distro, jiter) of openai automatically marked optional, content hash updated
nemoguardrails/cli/init.py	Added proper ImportError handling with helpful error message when openai is missing
.github/workflows/test-and-build-wheel.yml	Updated CI to install wheel with [server] extra since test starts a server

Sequence Diagram

sequenceDiagram
    participant User
    participant CLI as nemoguardrails CLI
    participant PyProject as pyproject.toml
    participant Server as nemoguardrails.server.api
    participant OpenAI as openai package

    Note over User,OpenAI: Without [server] extra installed
    User->>CLI: nemoguardrails server
    CLI->>Server: try: from nemoguardrails.server import api
    Server->>OpenAI: import openai
    OpenAI-->>Server: ImportError (not installed)
    Server-->>CLI: ImportError
    CLI->>User: Error: "openai package required. Install with: pip install nemoguardrails[server]"
    CLI->>User: Exit(1)

    Note over User,OpenAI: With [server] extra installed
    User->>CLI: pip install nemoguardrails[server]
    CLI->>PyProject: Read extras dependencies
    PyProject->>CLI: Install: aiofiles, openai
    User->>CLI: nemoguardrails server
    CLI->>Server: try: from nemoguardrails.server import api
    Server->>OpenAI: import openai
    OpenAI-->>Server: Success
    Server-->>CLI: Success
    CLI->>User: Server starts successfully

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[greptile-apps]

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[codecov]

Codecov Report

❌ Patch coverage is 40.00000% with 3 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
nemoguardrails/cli/__init__.py	40.00%	3 Missing ⚠️

📢 Thoughts on this report? Let us know!

[trebedea]

Looks good.