fix(mail): migrate filesystem helpers to fsUtils, update DKIM and mail APIs, harden SMTP client, and bump dependencies

ts/plugins.ts

@@ -93,3 +93,71 @@ export {
   uuid,
   ip,
 }
+
+// Filesystem utilities (compatibility helpers for smartfile v13+)
+export const fsUtils = {
+  /**
+   * Ensure a directory exists, creating it recursively if needed (sync)
+   */
+  ensureDirSync: (dirPath: string): void => {
+    fs.mkdirSync(dirPath, { recursive: true });
+  },
+
+  /**
+   * Ensure a directory exists, creating it recursively if needed (async)
+   */
+  ensureDir: async (dirPath: string): Promise<void> => {
+    await fs.promises.mkdir(dirPath, { recursive: true });
+  },
+
+  /**
+   * Write JSON content to a file synchronously
+   */
+  toFsSync: (content: any, filePath: string): void => {
+    const data = typeof content === 'string' ? content : JSON.stringify(content, null, 2);
+    fs.writeFileSync(filePath, data);
+  },
+
+  /**
+   * Write JSON content to a file asynchronously
+   */
+  toFs: async (content: any, filePath: string): Promise<void> => {
+    const data = typeof content === 'string' ? content : JSON.stringify(content, null, 2);
+    await fs.promises.writeFile(filePath, data);
+  },
+
+  /**
+   * Check if a file or directory exists
+   */
+  fileExistsSync: (filePath: string): boolean => {
+    return fs.existsSync(filePath);
+  },
+
+  /**
+   * Check if a file or directory exists (async)
+   */
+  fileExists: async (filePath: string): Promise<boolean> => {
+    try {
+      await fs.promises.access(filePath);
+      return true;
+    } catch {
+      return false;
+    }
+  },
+
+  /**
+   * Read a JSON file synchronously
+   */
+  toObjectSync: <T = any>(filePath: string): T => {
+    const content = fs.readFileSync(filePath, 'utf8');
+    return JSON.parse(content) as T;
+  },
+
+  /**
+   * Read a JSON file asynchronously
+   */
+  toObject: async <T = any>(filePath: string): Promise<T> => {
+    const content = await fs.promises.readFile(filePath, 'utf8');
+    return JSON.parse(content) as T;
+  },
+};