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.

rhai_tests/kubernetes/01_namespace_operations.rhai

@@ -1,5 +1,3 @@
-#!/usr/bin/env rhai
-
 // Test 1: Namespace Operations
 // This test covers namespace creation, existence checking, and listing
 

rhai_tests/kubernetes/02_pod_management.rhai

@@ -1,5 +1,3 @@
-#!/usr/bin/env rhai
-
 // Test 2: Pod Management Operations
 // This test covers pod creation, listing, retrieval, and deletion
 

rhai_tests/kubernetes/03_pcre_pattern_matching.rhai

@@ -1,5 +1,3 @@
-#!/usr/bin/env rhai
-
 // Test 3: PCRE Pattern Matching for Bulk Operations
 // This test covers the powerful pattern-based deletion functionality
 

rhai_tests/kubernetes/04_error_handling.rhai

@@ -1,5 +1,3 @@
-#!/usr/bin/env rhai
-
 // Test 4: Error Handling and Edge Cases
 // This test covers error scenarios and edge cases
 

rhai_tests/kubernetes/05_production_safety.rhai

@@ -1,5 +1,3 @@
-#!/usr/bin/env rhai
-
 // Test 5: Production Safety Features
 // This test covers timeouts, rate limiting, retry logic, and safety features
 

rhai_tests/kubernetes/run_all_tests.rhai

@@ -1,5 +1,3 @@
-#!/usr/bin/env rhai
-
 // Kubernetes Integration Tests - Main Test Runner
 // This script runs all Kubernetes integration tests in sequence