Keep the bench fixture in the CLI package

Move the benchmark target fixture under the CLI package so Node resolves its
workspace dependencies from the package that declares them.  This keeps the
repo-root Node test command from resolving @fedify/fedify and @fedify/vocab
through the root package scope.

#795 (comment)

Assisted-by: Codex:gpt-5.5

Author: dahlia

packages/cli/src/bench/action.test.ts

@@ -3,7 +3,7 @@ import { mkdtemp, writeFile } from "node:fs/promises";
 import { tmpdir } from "node:os";
 import { join } from "node:path";
 import test from "node:test";
-import { spawnBenchmarkTarget } from "../../../../test/bench/fixture.ts";
+import { spawnBenchmarkTarget } from "../../test/bench/fixture.ts";
 import runBench, { withUserAgent } from "./action.ts";
 import type { BenchCommand } from "./command.ts";