Function useExpressControllers

Mount controllers on an existing Express v5 app. Body parsing is the caller's responsibility — this function does NOT install express.json().

Mounting order:

1. Global @Middleware({type:'before'}) and function-form entries → app.use(...)
2. One express.Router() per controller → app.use(mountPath, router)
3. Global @Middleware({type:'after'}) non-error instances → app.use(...)
4. User error middleware (4-arg use) → app.use(errorHandler) [if defaultErrorHandler !== false]
5. libraryErrorMiddleware → app.use(libraryErrorMiddleware) [if defaultErrorHandler !== false]

Async because:

• Container.get() may return a Promise
• Arity detection for user error middleware requires resolving the class at boot
• Global interceptor resolution happens once before the controller loop