feat(security): add BeforeHandle hook for auth checks after model resolution

- Implement BeforeHandle hook to enforce authentication based on model rules.
- Integrate with existing security mechanisms to allow or deny access.
- Update documentation to reflect new hook and its usage.

pkg/mqttspec/hooks.go

@@ -20,8 +20,11 @@ type (
 	HookRegistry = websocketspec.HookRegistry
 )
 
-// Hook type constants - all 12 lifecycle hooks
+// Hook type constants - all lifecycle hooks
 const (
+	// BeforeHandle fires after model resolution, before operation dispatch
+	BeforeHandle = websocketspec.BeforeHandle
+
 	// CRUD operation hooks
 	BeforeRead   = websocketspec.BeforeRead
 	AfterRead    = websocketspec.AfterRead