fix: preserve Effect equality and scoped test lifetimes

[BleedingDev]

ScriptedAlchemy/effect-rstest#4 (origin of these fixes) | TechsioCZ/ontos#507 (consumer currently carrying them as a pnpm patch)

Why the change

Timed-out Effect tests and layer setups keep running after Rstest has moved on, and addEqualityTesters() breaks asymmetric matchers, so consumers patch the published package; this PR lands those fixes upstream so the patch can go away.

Special things to note

• Cleanup is awaited, not bounded: a finalizer that never completes will hold the suite. Native afterEach hooks run before onTestFinished and are outside the guarantee. Both are documented in the README.
• The two lifetime tests spawn a child Rstest (test/fixtures/run-fixture.ts) and assert the JSON report verbatim, including runner error strings like beforeAll hook timed out in 100ms. A future @rstest/core wording change will need those expectations updated.
• Schema property inputs and Effect.asVoid at the test boundary already exist here, so only the three behavioral fixes from the upstream PR are ported.

Change outline

Everything lives in src/internal/internal.ts; the rest is tests and docs.

 src/internal/internal.ts
   addEqualityTesters   # both sides must be Equal, else defer to Rstest
   runTest              # onTestFinished barrier awaits fiber settlement
   layer                # track setup fiber, interrupt it before Scope.close
 test/
+├── equality.test.ts               # semantic equal / not-equal, matchers intact
+├── test-values.test.ts            # thenable success values never resolved
+├── test-lifetime.test.ts          # child runner, hookTimeout 50
+├── layer-lifetime.test.ts         # child runner, hookTimeout 100
+└── fixtures/
+    ├── run-fixture.ts             # spawns rstest, decodes JSON report
+    ├── test-lifetime.fixture.ts
+    └── layer-lifetime.fixture.ts
 typetest/
+└── prop-schema.tst.ts             # mixed schema/arbitrary inference

Equality: with ||, a plain object versus an Equal value returned a hard false, so expect.objectContaining never got a turn.

 addEqualityTesters
-  if isEqual(a) || isEqual(b) -> Equal.equals(a, b)
+  if isEqual(a) && isEqual(b) -> Equal.equals(a, b)
   else -> undefined   # Rstest's own deep equality and asymmetric matchers

Test settlement: Rstest reports a timeout and immediately starts the next test; the fiber and its finalizers were still running.

 runTest(ctx)(effect)
+  ctx.onTestFinished(() => settlement, 0)   # registered before the run
   result = runPromise(effect, ctx)            # abort signal still cancels the fiber
+  settlement = result.then(noop, noop)        # swallow only for the barrier
   return result                               # timeout / failure / .fails unchanged

Layer teardown: suite hooks have no AbortSignal, so a beforeAll that exceeded its timeout kept building the layer while afterAll closed the scope underneath it.

 layer(...)
-  beforeAll -> runPromise(contextEffect)
+  beforeAll -> buildContext
+    withFiber(f => setupFiber = f; contextEffect)
   afterAll  -> closeScope
+    interrupt(setupFiber) if set
     Scope.close(scope)

How the lifetime tests verify it:

test-lifetime.test.ts
  runFixture("test-lifetime", 50)
    write temp rstest.config.mjs  (pool: threads, json reporter)
    execFile rstest run --config
    decode report.json via Schema
  assert summary {tests 25, failed 3, passed 20, skipped 2}
  assert failing names + messages are exactly the runner's own
  assert no unhandledErrors, no file errors

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