feat: Add Kubernetes examples and update dependencies

- Add Kubernetes examples demonstrating deployment of various
  applications (PostgreSQL, Redis, generic). This improves the
  documentation and provides practical usage examples.
- Add `tokio` dependency for async examples. This enables the use
  of asynchronous operations in the examples.
- Add `once_cell` dependency for improved resource management in
  Kubernetes module. This allows efficient management of
  singletons and other resources.

examples/kubernetes/clusters/redis.rhai

@@ -10,6 +10,35 @@ print("Creating Kubernetes manager for 'cache' namespace...");
 let km = kubernetes_manager_new("cache");
 print("✓ Kubernetes manager created");
 
+// Create the namespace if it doesn't exist
+print("Creating namespace 'cache' if it doesn't exist...");
+try {
+    create_namespace(km, "cache");
+    print("✓ Namespace 'cache' created");
+} catch(e) {
+    if e.to_string().contains("already exists") {
+        print("✓ Namespace 'cache' already exists");
+    } else {
+        print("⚠️ Warning: " + e);
+    }
+}
+
+// Clean up any existing resources first
+print("\nCleaning up any existing Redis resources...");
+try {
+    delete_deployment(km, "redis-cluster");
+    print("✓ Deleted existing deployment");
+} catch(e) {
+    print("✓ No existing deployment to delete");
+}
+
+try {
+    delete_service(km, "redis-cluster");
+    print("✓ Deleted existing service");
+} catch(e) {
+    print("✓ No existing service to delete");
+}
+
 // Create Redis cluster using the convenience method
 print("\nDeploying Redis cluster...");
 
@@ -19,6 +48,12 @@ try {
         "app": "redis-cluster",
         "type": "cache",
         "engine": "redis"
+    }, #{
+        "REDIS_PASSWORD": "redispassword",
+        "REDIS_PORT": "6379",
+        "REDIS_DATABASES": "16",
+        "REDIS_MAXMEMORY": "256mb",
+        "REDIS_MAXMEMORY_POLICY": "allkeys-lru"
     });
     print("✓ " + result);