Swift-Testing

A broad withKnownIssue wrapper treated missing snapshots as expected failures. Narrow the matcher, then prove a wrong rendered state fails.

A serialized Swift Testing suite lost files to another suite's initializer. Inject startup cleanup so ordinary test construction leaves shared files alone.

A polling test helper failed with "ContinuousClock.now < deadline" only when its target ran in parallel. Snapshot suites held the main actor, so the wait got 3 to 5 turns in 5 seconds. A 60-second timeout would have hidden it. A turn budget fixed it, and a mutation showed that a real hang still fails within 5 seconds.