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/run-task.ts

@@ -0,0 +1,59 @@
+import { existsSync } from "node:fs";
+import { readFile } from "node:fs/promises";
+import { fileURLToPath } from "node:url";
+import { join } from "node:path";
+import { CLI_DIR } from "./helpers/paths.ts";
+import { spawnProcess } from "./helpers/process.ts";
+
+type Task = { test?: string[]; filter?: string; script?: string; tasks?: string[]; command?: string; args?: string[] };
+const taskDirectory = import.meta.dirname;
+
+export async function runTask(name: string, extraArgs: string[] = []): Promise<number> {
+    if (Number(process.versions.node.split(".")[0]) < 26) throw new Error("CLI E2E tests require Node.js 26 or newer");
+    const tasks = JSON.parse(await readFile(new URL("./tasks.json", import.meta.url), "utf8")) as Record<string, Task>;
+    const task = tasks[name];
+    if (!task) throw new Error(`Unknown CLI task '${name}'. Available tasks: ${Object.keys(tasks).join(", ")}`);
+    if (task.tasks) {
+        for (const child of task.tasks) {
+            const code = await runTask(child, extraArgs);
+            if (code !== 0) return code;
+        }
+        return 0;
+    }
+    const envFile = join(CLI_DIR, ".test.env");
+    const envArgs = existsSync(envFile) ? [`--env-file=${envFile}`] : [];
+    let command = process.execPath;
+    let args: string[];
+    if (task.test) {
+        args = [
+            ...envArgs,
+            "--test",
+            "--test-concurrency=1",
+            ...(task.filter ? [`--test-name-pattern=${task.filter}`] : []),
+            ...extraArgs,
+            ...task.test.map((file) => fileURLToPath(new URL(file, import.meta.url))),
+        ];
+    } else if (task.script) {
+        args = [...envArgs, fileURLToPath(new URL(task.script, import.meta.url)), ...extraArgs];
+    } else if (task.command) {
+        command = task.command;
+        args = [...(task.args ?? []), ...extraArgs];
+    } else throw new Error(`CLI task '${name}' has no executable entry point`);
+    const child = spawnProcess(command, {
+        args,
+        cwd: taskDirectory,
+        stdin: "inherit",
+        stdout: "inherit",
+        stderr: "inherit",
+    });
+    return (await child.status).code;
+}
+
+if (import.meta.main) {
+    try {
+        process.exitCode = await runTask(process.argv[2] ?? "test", process.argv.slice(3));
+    } catch (error) {
+        console.error(error);
+        process.exitCode = 1;
+    }
+}