Fix pre-existing shfmt drift in check-evidence-tutorials.sh

`shfmt -d docs/site/scripts/check-evidence-tutorials.sh` reports drift that predates the Casework tutorial work: the alignment of the comment columns in the `EXCLUDED_EVIDENCE_TUTORIALS` block (`first-breg`, `publish-and-consume-discovery-index`, `review-registry-changes` lines) and a line continuation in `prepare_toolset`. `shellcheck` is clean apart from the existing SC2016 notes.

Run `shfmt -w` on the file and check that `docs/site` `npm test` still passes (the Evidence gate tests parse the excluded list).

Triage: later, chore.

Start with docs/site/scripts/check-evidence-tutorials.sh and run shfmt -w on the file. Verify that the listed exclusions and prepare_toolset formatting no longer produce shfmt drift, then run npm test in docs/site; done means the tests pass and shellcheck remains clean apart from the noted SC2016 messages.

Written by the indexing model from the issue text.