chore(repo): run the mutation lane on the released 12.1.0 CLI

[systemfsoftware-maker]

Summary

The Mutation workflow on main has failed since #117 with "infrastructure failure": every shard either exits 3 with No files to instrument or is killed at the 30-minute cap with zero completed mutants.

The lane dogfoods the published CLI through catalog:stryker (latest), but the lockfile still pinned @systemfsoftware/stryker-js 11.0.0 and the TypeScript checker 7.1.0. Both predate the fixes the lane depends on:

• fix(repo): pass a mutate set that matches no file with an empty report #115: a mutate set that matches no file writes an empty report. On 11.0.0 an empty shard, such as shards 2 and 3 of the one-file checker package, fails at the instrument stage.
• fix(repo): make mutation CI fail truthfully and actually mutate #117: the checker checks mutated files and their dependents instead of the whole program per mutant. On 7.1.0 no mutant completes before the cap.

This PR refreshes the lockfile to the versions released by #116: stryker-js 12.1.0, typescript-checker 7.1.2, vitest-runner 7.3.0 and test-contribution 4.1.1. The catalog specifiers stay latest.

It also fixes a flaky e2e scenario, "failing checker emits structured StageError". Its test file src/service.vm.test.ts was a CommonJS assert script written for the deleted node:vm harness. Vitest registers no tests from that file, so the dry run failed with "No tests were executed" and raced the checker's missing-tsconfig failure. The scenario passed only when the checker failed first: CI was green on main at a1057e2aa, red on this PR, and red on every local run, including on a1057e2aa. The file now contains the same three assertions as Vitest tests, so the checker failure is the only failure left. tests/typescript-checker.e2e.test.ts passes 7/7 locally.

Validation

Local runs of the checker package's pnpm mutation, the same command the lane runs:

CLI	Shard	Result
11.0.0 (main's lockfile)	1/1, 157 mutants	0 completed after 900 s, killed
12.1.0 (this PR)	1/1, 157 mutants	157 completed in 29 s: 114 CompileError, 25 Killed, 9 Survived, 9 Ignored
12.1.0 (this PR)	2/3, no files	exit 0, empty report

The 12.1.0 run exits 1 because its score (73.53) is under the shared break: 100 threshold. scripts/mutation-job.ts fails a job only when a package leaves no report, so this is reported as a score, not a job failure.

The Mutation workflow runs only on pushes to main, so it runs for the first time after this merges.