Add tests for integration-level intellisense checks

Integration-level IntelliSense checks are about verifying what symbols, methods, properties, and type information are actually visible to external tools (like IDEs, LSPs, or static analyzers) when someone uses a Python library. Since IntelliSense is not part of Python's runtime, the idea is to simulate the perspective of a developer using the Python library in an IDE or editor. These checks are most commonly done using tools like [jedi](https://jedi.readthedocs.io/en/latest/).

The issue names no files, tests, or entry points. Start by reviewing the repository's existing integration-test layout and the linked Jedi documentation, then define checks for externally visible symbols, methods, properties, and type information. Done means these IntelliSense checks run against the Python library and verify the intended developer-facing API.

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