fix: reference correct PyPI package names in provider load error messages

[jsonbailey]

Summary

• The provider load error message previously referenced internal Python module names (ldai_openai, ldai_langchain) rather than the pip-installable PyPI package names, making the error unhelpful to end users.
• Added a _PYPI_PACKAGE_NAMES mapping in runner_factory.py that maps internal module names to their corresponding PyPI package names.
• _pkg_exists now raises an ImportError that includes the PyPI package name and an actionable pip install command (e.g. pip install launchdarkly-server-sdk-ai-openai).
• Simplified the warning log in _get_provider_factory — it now forwards the ImportError message directly, which already contains the install guidance.
• Added tests/test_runner_factory.py covering _pkg_exists, _PYPI_PACKAGE_NAMES, and _get_provider_factory warning content.

Before:

WARNING:ldclient.util:Could not load provider 'openai': Package 'ldai_openai' not found. Make sure the corresponding package is installed.

After:

WARNING:ldclient.util:Could not load provider 'openai': Package 'launchdarkly-server-sdk-ai-openai' not found. Run: pip install launchdarkly-server-sdk-ai-openai

Test plan

• All existing tests pass (uv run pytest tests/ -x -q — 185 passed)
• New tests/test_runner_factory.py verifies the PyPI name appears in both the ImportError and the warning log for openai and langchain providers
• Verified the old boilerplate "Make sure the corresponding package is installed" text is no longer present in warnings

🤖 Generated with Claude Code

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Note

Low Risk
Low risk: only adjusts ImportError/warning messaging when optional provider dependencies are absent and adds unit tests; no runtime behavior changes when providers are installed.

Overview
Improves provider-load failure messaging in RunnerFactory by introducing a _PYPI_PACKAGE_NAMES mapping and emitting errors that reference the pip-installable package names (instead of internal module names) when ldai_openai/ldai_langchain aren’t importable.

Simplifies _get_provider_factory’s ImportError warning to log the exception message directly, and adds test_runner_factory.py to validate the mapping and that warnings/errors include PyPI names and remain package-manager agnostic.

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