Rename RuntimeEnvironment to RunEnv

[pda]

This is a Test Engine run_env; for a “Run” in Test Engine.

[Copilot]

Pull Request Overview

This PR renames the RuntimeEnvironment class and all its references to RunEnv to streamline naming across the codebase.

• Renamed the RuntimeEnvironment class and updated imports in source and test files
• Updated function signatures and return types to use RunEnv
• Adjusted variable names and type hints in tests to match the new class name

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
tests/buildkite_test_collector/conftest.py	Updated import and fixture return type to RunEnv
tests/buildkite_test_collector/collector/test_run_env.py	Replaced runtime_env references with run_env
src/buildkite_test_collector/collector/run_env.py	Renamed class, functions, and updated module docstring
src/buildkite_test_collector/collector/payload.py	Updated import and type annotations to RunEnv

Comments suppressed due to low confidence (3)

src/buildkite_test_collector/collector/run_env.py:1

• [nitpick] The module-level docstring is terse and doesn’t describe its purpose clearly. Consider expanding it to explain that this module detects and represents CI run environments for the test engine.

"""Test Engine run_env"""

src/buildkite_test_collector/collector/run_env.py:94

• [nitpick] The class docstring The detected RunEnv is tautological. You may want to expand it to explain what fields this class provides and how it’s used to represent CI environment data.

class RunEnv:

src/buildkite_test_collector/collector/run_env.py:20

• Module-private functions are usually prefixed with a single underscore. Consider renaming __buildkite_env (and other double-underscore helpers) to _buildkite_env to follow PEP 8 conventions.

def __buildkite_env() -> Optional['RunEnv']: