Add DM test suites and headless e2e CI

scripts/run-targeted-tests.mjs

@@ -0,0 +1,57 @@
+import { spawn } from "node:child_process";
+import { access } from "node:fs/promises";
+import { fileURLToPath } from "node:url";
+import path from "node:path";
+
+const rootDir = path.dirname(fileURLToPath(new URL("../package.json", import.meta.url)));
+const setupImport = new URL("../tests/test-helpers/setup-localstorage.mjs", import.meta.url);
+const requestedFiles = process.argv.slice(2);
+
+if (!requestedFiles.length) {
+  console.error("No test files provided. Usage: node scripts/run-targeted-tests.mjs <file...>");
+  process.exit(1);
+}
+
+const testFiles = requestedFiles.map((file) =>
+  path.isAbsolute(file) ? file : path.join(rootDir, file),
+);
+
+for (const testFile of testFiles) {
+  try {
+    await access(testFile);
+  } catch (error) {
+    console.error(`Test file not found: ${testFile}`);
+    throw error;
+  }
+}
+
+for (const testFile of testFiles) {
+  const relativePath = path.relative(rootDir, testFile);
+  console.log(`\n→ Running ${relativePath}`);
+
+  await new Promise((resolve, reject) => {
+    const child = spawn(process.execPath, ["--import", setupImport.href, testFile], {
+      stdio: "inherit",
+    });
+
+    child.on("close", (code, signal) => {
+      if (signal) {
+        reject(new Error(`${relativePath} exited with signal ${signal}`));
+        return;
+      }
+
+      if (code !== 0) {
+        reject(new Error(`${relativePath} failed with exit code ${code}`));
+        return;
+      }
+
+      resolve();
+    });
+
+    child.on("error", (error) => {
+      reject(error);
+    });
+  });
+}
+
+console.log("\n✔ Targeted tests passed");