Runtime Tests

• Use it.effect for Effect-returning tests and regular it for pure synchronous tests.
• it.effect and it.live provide and close a Scope; return scoped effects directly instead of wrapping the body in Effect.scoped.
• Use assert from @effect/vitest, not Vitest's expect.
• Use TestClock for time-dependent behavior.
• Keep Effect.runSync out of unit tests; runnable documentation follows the root JSDoc validation rules.

Inspect nearby tests for imports and structure. This branch is complete when every changed behavior has focused coverage and its targeted test passes.