Run pytest test suites on stations

Pytest is now a first-class procedure framework alongside OpenHTF and the TofuPilot Framework. Each test function becomes a phase, and recognized assert shapes are promoted to measurements with validators on the dashboard, no SDK imports required.

• Added a pytest connector that streams phase events live and bundles measurements per phase
• Added AST extraction for numeric ranges, single bounds, equality, pytest.approx, string equality and membership, and boolean asserts
• Added support for multiple measurements in one test (distinct identifiers) and stacked validators on one measurement (repeated asserts on the same identifier)
• Added a Pytest Starter template in the New Procedure picker so you can clone and run in one click