Add comprehensive native cost monitoring system for all cloud providers

This major enhancement adds built-in cost tracking and optimization features to Clustrix:

## New Features
- **Cost Tracking Decorator**: @cost_tracking_decorator('provider', 'instance_type')
- **Manual Cost Monitoring**: start_cost_monitoring(), generate_cost_report()
- **Multi-Provider Support**: Lambda Cloud, AWS, Azure, GCP cost monitoring
- **Resource Utilization Tracking**: CPU, memory, GPU usage monitoring
- **Cost Optimization Recommendations**: Provider-specific savings suggestions

## Implementation Details
- Abstract base class (BaseCostMonitor) for extensible provider support
- Provider-specific implementations with accurate pricing data
- Comprehensive unit tests (37 tests, all passing)
- Automatic cost estimation with spot/preemptible instance support
- Regional pricing comparisons and batch workload cost estimation

## Tutorial Updates
All cloud provider tutorials now use native cost monitoring functions:
- Lambda Cloud: Updated with @cost_tracking_decorator examples
- AWS: Added EC2 and Batch cost monitoring with spot instance analysis
- Azure: Integrated VM and Batch cost tracking with spot VM savings
- GCP: Comprehensive cost analysis with preemptible VMs and sustained use discounts

## API Exports
New functions available in clustrix module:
- cost_tracking_decorator, get_cost_monitor, start_cost_monitoring
- generate_cost_report, get_pricing_info
- ResourceUsage, CostEstimate, CostReport classes

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: jeremymanning

clustrix/__init__.py

@@ -4,6 +4,16 @@
 from .local_executor import LocalExecutor, create_local_executor
 from .loop_analysis import detect_loops_in_function, find_parallelizable_loops
 from .utils import setup_environment
+from .cost_monitoring import (
+    cost_tracking_decorator,
+    get_cost_monitor,
+    start_cost_monitoring,
+    generate_cost_report,
+    get_pricing_info,
+    ResourceUsage,
+    CostEstimate,
+    CostReport,
+)
 
 __version__ = "0.1.0"
 __all__ = [
@@ -16,4 +26,12 @@
     "detect_loops_in_function",
     "find_parallelizable_loops",
     "setup_environment",
+    "cost_tracking_decorator",
+    "get_cost_monitor",
+    "start_cost_monitoring",
+    "generate_cost_report",
+    "get_pricing_info",
+    "ResourceUsage",
+    "CostEstimate",
+    "CostReport",
 ]