Name the mypy Target Key in the python-codestyle Profiles #3787

Problem

validate-task.yml's Type check Python step passes mypy no path where the config it reads sits in the directory it checks. A [tool.mypy] section with no files, packages, or modules key then exits 2 with "Missing target module, package, files, or command".

The python-codestyle skill's lint-only profile does not tell a carrier it owes that key. The hub's own pyproject.toml sets files, which is why the hub never sees the failure. A lint-only directory whose [tool.mypy] section holds only strict = true reproduces it.

docs/reusable-workflows.md "Adopting the Gates" now names the key, as part of the #1516 fix on feature/burn-3334. The skill's profile text is outside that change's file claim, so it is filed here.

Done when

The python-codestyle lint-only profile (and its build profile, if it has the same gap) says that a [tool.mypy] section names its target, for example files = ["."].