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/measuredCli.ts

@@ -0,0 +1,62 @@
+import { runProcess } from "./process.ts";
+import { CLI_DIR, CLI_DIST } from "./cli.ts";
+
+export type CliProcessMeasurement = {
+    elapsedMs: number;
+    userCpuMs: number;
+    systemCpuMs: number;
+    totalCpuMs: number;
+    cpuToWallRatio: number;
+    maxResidentSetKiB: number;
+};
+
+const MARKER = "__LIVESYNC_GNU_TIME__";
+
+export async function runMeasuredCliOrFail(...args: string[]): Promise<CliProcessMeasurement> {
+    const started = performance.now();
+    let output: Awaited<ReturnType<typeof runProcess>>;
+    try {
+        output = await runProcess("/usr/bin/time", {
+            args: ["-f", `${MARKER}%U\t%S\t%M`, process.execPath, CLI_DIST, ...args],
+            cwd: CLI_DIR,
+            stdin: "null",
+            stdout: "piped",
+            stderr: "piped",
+        });
+    } catch (error) {
+        if (typeof error === "object" && error !== null && "code" in error && error.code === "ENOENT") {
+            throw new Error(
+                "GNU /usr/bin/time is required for the compression benchmark. Use the Compose runner or install GNU time."
+            );
+        }
+        throw error;
+    }
+    const elapsedMs = performance.now() - started;
+    const stderr = new TextDecoder().decode(output.stderr);
+    const stdout = new TextDecoder().decode(output.stdout);
+    const measurementLine = stderr.split(/\r?\n/).find((line) => line.startsWith(MARKER));
+    if (!output.success) {
+        throw new Error(`CLI exited with code ${output.code}\nstdout: ${stdout}\nstderr: ${stderr}`);
+    }
+    if (!measurementLine) {
+        throw new Error(`GNU time did not emit the expected measurement marker\nstderr: ${stderr}`);
+    }
+    const [userSeconds, systemSeconds, maxResidentSetKiB] = measurementLine
+        .slice(MARKER.length)
+        .split("\t")
+        .map(Number);
+    if (![userSeconds, systemSeconds, maxResidentSetKiB].every(Number.isFinite)) {
+        throw new Error(`Could not parse GNU time measurement: ${measurementLine}`);
+    }
+    const userCpuMs = userSeconds * 1000;
+    const systemCpuMs = systemSeconds * 1000;
+    const totalCpuMs = userCpuMs + systemCpuMs;
+    return {
+        elapsedMs: Number(elapsedMs.toFixed(1)),
+        userCpuMs: Number(userCpuMs.toFixed(1)),
+        systemCpuMs: Number(systemCpuMs.toFixed(1)),
+        totalCpuMs: Number(totalCpuMs.toFixed(1)),
+        cpuToWallRatio: Number((totalCpuMs / elapsedMs).toFixed(4)),
+        maxResidentSetKiB,
+    };
+}