Initial commit: Complete NodeJS-native setup

- Migrated from Python pre-commit to NodeJS-native solution
- Reorganized documentation structure
- Set up Husky + lint-staged for efficient pre-commit hooks
- Fixed Dockerfile healthcheck issue
- Added comprehensive documentation index

services/auth/auth.error.ts

@@ -0,0 +1,43 @@
+import { NextFunction, Request, Response } from 'express';
+
+/**
+ * Custom AuthError class that extends Error with HTTP status code
+ * Security: Provides consistent error handling for authentication issues
+ */
+export class AuthError extends Error {
+  statusCode: number;
+
+  constructor(message: string, statusCode: number = 401) {
+    super(message);
+    this.statusCode = statusCode;
+    this.name = 'AuthError';
+  }
+}
+
+/**
+ * Middleware to handle AuthError exceptions
+ * Security: Centralized error handling for authentication errors
+ */
+export const handleAuthError = (
+  err: Error,
+  req: Request,
+  res: Response,
+  next: NextFunction
+) => {
+  if (err instanceof AuthError) {
+    return res.status(err.statusCode).json({
+      error: err.message,
+      statusCode: err.statusCode,
+    });
+  }
+
+  // Handle JWT verification errors
+  if (err.name === 'JsonWebTokenError' || err.name === 'TokenExpiredError') {
+    return res.status(401).json({
+      error: 'Invalid or expired token',
+      statusCode: 401,
+    });
+  }
+
+  next(err);
+};