test third party release tooling in plan

as we add features that rely on installing and orchestrating third party tools at release time, we expose users to potential "run time" failure modes: things that can cause a release to go red.

specifically, if you add a dist feature that leverages a third party tool, we should, at minimum, ensure that that tool is installable on every platform you intend to run it on. and we should do this in the plan stage.

i would anticipate that this requires constructing a list of all third party tools and then matrix for all build platforms. plan should proceed to install each tool on each platform, and should fail if any tool fails to build on any specfied platform.

The issue names no files, tests, or entry points. Start by mapping how the plan stage discovers distribution features, third-party tools, and target platforms, then determine how installation checks should be represented and executed. Done means every specified tool is tested on every intended platform and plan fails when a tool cannot be installed.

Written by the indexing model from the issue text.