fix(mitm): generate root ca on server startup (#2228)

Direct MITM server startup read rootCA.key/.crt immediately and exited
when either was missing, bypassing the manager.js CA setup path.

- generate Root CA from server.js when key/cert is missing
- make generateRootCA()/generateCert() synchronous to avoid a startup
  race before readFileSync
- add unit test covering synchronous Root CA creation

Co-authored-by: Cursor <cursoragent@cursor.com>

tests/unit/mitm-root-ca.test.js

@@ -0,0 +1,35 @@
+import { describe, expect, it } from "vitest";
+import { createRequire } from "module";
+import fs from "fs";
+import os from "os";
+import path from "path";
+
+const require = createRequire(import.meta.url);
+
+function loadRootCAWithDataDir(dataDir) {
+  const rootCAPath = require.resolve("../../src/mitm/cert/rootCA.js");
+  const pathsPath = require.resolve("../../src/mitm/paths.js");
+  delete require.cache[rootCAPath];
+  delete require.cache[pathsPath];
+
+  const oldDataDir = process.env.DATA_DIR;
+  process.env.DATA_DIR = dataDir;
+  try {
+    return require("../../src/mitm/cert/rootCA.js");
+  } finally {
+    if (oldDataDir === undefined) delete process.env.DATA_DIR;
+    else process.env.DATA_DIR = oldDataDir;
+  }
+}
+
+describe("MITM Root CA generation", () => {
+  it("creates Root CA files synchronously for direct server startup", () => {
+    const dataDir = fs.mkdtempSync(path.join(os.tmpdir(), "9router-mitm-ca-"));
+    const { generateRootCA } = loadRootCAWithDataDir(dataDir);
+
+    generateRootCA();
+
+    expect(fs.existsSync(path.join(dataDir, "mitm", "rootCA.key"))).toBe(true);
+    expect(fs.existsSync(path.join(dataDir, "mitm", "rootCA.crt"))).toBe(true);
+  });
+});