fix(client-react): typecheck the package's own tests instead of excluding them

`check:type-check-coverage` failed on the first push, and it was right. The
initial commit added `**/*.test.tsx` to tsconfig's `exclude` to match the
`**/*.test.ts` entry every sibling package carries — but that entry is frozen
DEBT the repo is migrating away from (#4311), not a convention to copy. The
gate's own summary makes it explicit: 21 packages still exclude their tests,
carrying 2243 frozen raw errors in TEST_DEBT. Excluding one more would have
reported green over source `tsc` never read.

Drops the test exclusion entirely, so client-react typechecks its own tests and
stays out of that ledger.

Doing so immediately surfaced a real gap: the `METADATA_EVENT` fixture was
declared and never used, because `useMetadataSubscription` was covered for
re-subscription and unmount but not for delivery. Adds that assertion rather
than deleting the fixture — 18 tests now.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LYnZrTwXbrctB8E8HpJAPT

Author: claude

packages/client-react/src/realtime-hooks.test.tsx

@@ -329,6 +329,19 @@ describe('#4682 events reach the caller', () => {
     expect(result.current?.type).toBe('data.records.updated');
   });
 
+  it('useMetadataSubscription exposes the latest metadata event', () => {
+    const { client, metadata } = createFakeClient();
+    const { result } = renderHook(() => useMetadataSubscription('object'), {
+      wrapper: wrapperFor(client),
+    });
+
+    expect(result.current).toBeNull();
+
+    act(() => metadata[0].deliver(METADATA_EVENT));
+
+    expect(result.current).toEqual(METADATA_EVENT);
+  });
+
   it('useDataSubscriptionCallback forwards the event without re-rendering state', () => {
     const { client, data } = createFakeClient();
     const seen: DataEvent[] = [];

packages/client-react/tsconfig.json

@@ -10,5 +10,5 @@
     "types": ["node", "react"]
   },
   "include": ["src/**/*"],
-  "exclude": ["node_modules", "dist", "**/*.test.ts", "**/*.test.tsx"]
+  "exclude": ["node_modules", "dist"]
 }