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.

src/apps/cli/vite.config.ts

@@ -49,26 +49,6 @@ if (typeof globalThis.FileReader === "undefined") {
 }
 `;
 
-function injectBanner(): import("vite").Plugin {
-    return {
-        name: "inject-banner",
-        generateBundle(_options, bundle) {
-            for (const chunk of Object.values(bundle)) {
-                if (chunk.type === "chunk" && chunk.isEntry) {
-                    // Insert after the shebang line if present, otherwise at the top.
-                    if (chunk.code.startsWith("#!")) {
-                        const newline = chunk.code.indexOf("\n");
-                        chunk.code =
-                            chunk.code.slice(0, newline + 1) + fileReaderPolyfillBanner + chunk.code.slice(newline + 1);
-                    } else {
-                        chunk.code = fileReaderPolyfillBanner + chunk.code;
-                    }
-                }
-            }
-        },
-    };
-}
-
 const buildInputs: Record<string, string> = {
     index: resolve(__dirname, "entrypoint.ts"),
 };
@@ -77,7 +57,7 @@ if (process.env.LIVESYNC_CLI_TEST_SUPPORT === "1") {
 }
 
 export default defineConfig({
-    plugins: [svelte(), injectBanner()],
+    plugins: [svelte()],
     resolve: {
         // This bundle runs in Node. Vite's client defaults include the `browser`
         // export condition, which would select Commonlib's inline Web Worker.
@@ -98,7 +78,16 @@ export default defineConfig({
         outDir: "dist",
         emptyOutDir: true,
         minify: false,
+        sourcemap: process.env.LIVESYNC_CLI_COVERAGE === "1",
         rollupOptions: {
+            output: {
+                banner: (chunk) => (chunk.isEntry ? fileReaderPolyfillBanner : ""),
+                // c8 filters mapped ranges before resolving relative source paths.
+                sourcemapPathTransform:
+                    process.env.LIVESYNC_CLI_COVERAGE === "1"
+                        ? (source: string, mapPath: string) => path.resolve(path.dirname(mapPath), source)
+                        : undefined,
+            },
             input: buildInputs,
             external: (id) => {
                 if (isBuiltin(id)) return true;