Fix no-op logger setup in client test

[paskal]

lgr.Out returns an Option; it does not change anything by itself. app/cmd/client_test.go:31-32 calls it twice as a bare statement, so the test neither redirects log output to io.Discard for its duration nor restores stdout afterwards, and TestClient prints through as before. Wrapping both calls in lgr.Setup, the form used everywhere else in the tree, makes the intent work.

staticcheck also reports the deferred line, though only on some toolchains, which is presumably why it has never shown up in CI. With the golangci-lint version pinned in .github/workflows/ci.yml:

$ golangci-lint cache clean && golangci-lint run      # darwin/arm64, go1.26.7
app/cmd/client_test.go:32:2: SA9010: deferred return function not called (staticcheck)
	defer lgr.Out(os.Stdout)

$ docker run --rm -v "$PWD":/app -w /app golangci/golangci-lint:v2.12.2 golangci-lint run
0 issues.                                             # linux/arm64, go1.26.2

The change clears it in both environments, and the tests pass with -race against mongo 4.4 and mongo 8.