ci(skills): remove the ruff-format skip once the formatting churn lands

[potiuk]

Follow-up to #1054, which turned on lint, type-check and test for the Python under skills/ but deliberately skipped the formatter:

[tool.magpie.checks]
skip = ["ruff-format"]

The reason is sound and recorded in skills/pyproject.toml: folding a mechanical reformat into the change that turns the checks on buries the reviewable part behind churn nobody can read line by line. This issue exists so the skip does not quietly become permanent — the comment says "after which this skip can be deleted" and nothing was tracking it.

Size of the job

Measured on the #1054 branch with uv run ruff format --diff under skills/:

Files reformatted	6
Lines removed	94
Lines added	187
Total churn	269

All of it is the formatter reflowing things that are merely long — set literals like MACOS_X64 in ci-runner-audit/scripts/scan_ci_runners.py exploded one element per line, and long re.compile(...) constants wrapped across lines. No logic moves.

What to do

1. Run uv run --directory skills ruff format . and commit the result on its own, touching nothing else.
2. Delete the [tool.magpie.checks] block from skills/pyproject.toml — with ruff-format no longer skipped, run-workspace-check.sh picks it up automatically from the [tool.ruff] section already present.
3. Confirm prek run --all-files is green.

Why it is a good first issue

The change is entirely mechanical and the tooling decides the outcome — there is nothing to design. The only judgement needed is not mixing anything else into the commit, which is the point of doing it separately.

Worth doing reasonably soon: every new script added under skills/ before this lands is written against an unformatted baseline, so the eventual diff only grows.