010 T2: C# sweep: singular `.Test.cs` + `.GodotTest.cs`, delete `tests/` dirs nf-9wto ← Beads

Twinned from https://github.com/cfsh/ninefold/issues/1002 by tools/beads/import_github.py's reconcile pass.

From 010-co-located-tests-and-probes.md's task table (design 010). - Real dependency: T1 - Note: the lane is T2's correctness check — a partial rename fails it mechanically