feat(config): add security feature toggle support

Implements a master toggle for security features across config,
CLI, and application logic. This allows granular control over
whether the advanced security middleware and protections are
active globally.

lib/server/admin_security_test.go

@@ -111,7 +111,9 @@ func setupAdminSecurityTest(t *testing.T) (*App, *gin.Engine) {
 		alertStore:    alerts.NewStore(filepath.Join(cfg.DBDir, "alerts.json")),
 		securityGuard: security.NewGuard(),
 	}
-	app.reloadSecurityConfig()
+	if err := app.reloadSecurityConfig(); err != nil {
+		t.Fatalf("reload security config: %v", err)
+	}
 	t.Cleanup(func() { _ = app.securityGuard.Close() })
 
 	router := gin.New()