By: Michael Lynch <git@mtlynch.io>
Construct test fixtures with shared generic helpers Port MustCreate and MustCreate2 from refactoring-english-feedback. Both helpers use the supplied constructor and fail the calling test when it rejects the input, rather than requiring a wrapper for each value type. Migrate test callers and remove redundant test-only constructor helpers. Keep panic helpers that still have production callers. Cover successful construction and fatal error handling for both generic helpers.