Migrate CLI E2E tests to Node.js 26

Run the CLI subprocess suites and benchmark tools as native TypeScript with
node:test, and move them under test/e2e-cli.

Update CI and Compose runners, run local smoke tests on Linux, macOS, and
Windows, and collect source-mapped CLI coverage with c8.

test/e2e-cli/helpers/temp.ts

@@ -0,0 +1,20 @@
+import { mkdtemp, rm } from "node:fs/promises";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+
+/** A temporary directory which is removed when its `await using` scope ends. */
+export class TempDir implements AsyncDisposable {
+    readonly path: string;
+    private constructor(path: string) {
+        this.path = path;
+    }
+    static async create(prefix = "livesync-node-test"): Promise<TempDir> {
+        return new TempDir(await mkdtemp(join(tmpdir(), `${prefix}.`)));
+    }
+    join(...parts: string[]): string {
+        return join(this.path, ...parts);
+    }
+    async [Symbol.asyncDispose](): Promise<void> {
+        await rm(this.path, { recursive: true, force: true }).catch(() => {});
+    }
+}