Clean up default configurations and remove placeholder cloud examples (#35)

- Remove redundant cloud provider configurations (AWS, GCP, Azure)
- Keep only functional configurations: local, Kubernetes, and HPC clusters
- Prepare for proper cloud provider integrations with API-based setup
- Reorganize configs in logical order: local first, then HPC examples

The removed cloud examples were just static placeholders that didn't actually
provision resources. They will be replaced with proper implementations that:
- Accept user credentials/API keys
- Automatically provision cloud resources
- Handle cluster lifecycle management

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

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

Author: jeremymanning

clustrix/notebook_magic.py

@@ -201,6 +201,16 @@ class widgets:  # type: ignore
         "default_memory": "16GB",
         "description": "Local machine using all available cores",
     },
+    "Local Kubernetes": {
+        "name": "Local Kubernetes",
+        "cluster_type": "kubernetes",
+        "k8s_namespace": "default",
+        "k8s_image": "python:3.11",
+        "default_cores": 2,
+        "default_memory": "4GB",
+        "package_manager": "pip",
+        "description": "Local Kubernetes cluster (Docker Desktop/minikube)",
+    },
     "University SLURM Cluster": {
         "name": "University SLURM Cluster",
         "cluster_type": "slurm",
@@ -249,94 +259,6 @@ class widgets:  # type: ignore
         "package_manager": "pip",
         "description": "Example SSH remote server configuration",
     },
-    "Local Kubernetes": {
-        "name": "Local Kubernetes",
-        "cluster_type": "kubernetes",
-        "k8s_namespace": "default",
-        "k8s_image": "python:3.11",
-        "default_cores": 2,
-        "default_memory": "4GB",
-        "package_manager": "pip",
-        "description": "Local Kubernetes cluster (Docker Desktop/minikube)",
-    },
-    "AWS EKS Cluster": {
-        "name": "AWS EKS Cluster",
-        "cluster_type": "kubernetes",
-        "cluster_host": "cluster-api.region.eks.amazonaws.com",
-        "cluster_port": 443,
-        "k8s_namespace": "default",
-        "k8s_image": "python:3.11",
-        "default_cores": 4,
-        "default_memory": "8GB",
-        "package_manager": "pip",
-        "cost_monitoring": True,
-        "description": "Amazon EKS cluster configuration",
-    },
-    "GCP GKE Cluster": {
-        "name": "GCP GKE Cluster",
-        "cluster_type": "kubernetes",
-        "cluster_host": "gke-cluster.googleapis.com",
-        "cluster_port": 443,
-        "k8s_namespace": "default",
-        "k8s_image": "python:3.11",
-        "default_cores": 4,
-        "default_memory": "8GB",
-        "package_manager": "pip",
-        "cost_monitoring": True,
-        "description": "Google GKE cluster configuration",
-    },
-    "Azure AKS Cluster": {
-        "name": "Azure AKS Cluster",
-        "cluster_type": "kubernetes",
-        "cluster_host": "aks-cluster.region.azmk8s.io",
-        "cluster_port": 443,
-        "k8s_namespace": "default",
-        "k8s_image": "python:3.11",
-        "default_cores": 4,
-        "default_memory": "8GB",
-        "package_manager": "pip",
-        "cost_monitoring": True,
-        "description": "Azure AKS cluster configuration",
-    },
-    "AWS EC2 via SSH": {
-        "name": "AWS EC2 via SSH",
-        "cluster_type": "ssh",
-        "cluster_host": "ec2-xx-xx-xx-xx.compute-1.amazonaws.com",
-        "username": "ec2-user",
-        "cluster_port": 22,
-        "default_cores": 8,
-        "default_memory": "32GB",
-        "remote_work_dir": "/home/ec2-user/clustrix",
-        "package_manager": "conda",
-        "cost_monitoring": True,
-        "description": "AWS EC2 instance accessed via SSH",
-    },
-    "GCP Compute via SSH": {
-        "name": "GCP Compute via SSH",
-        "cluster_type": "ssh",
-        "cluster_host": "instance-name.zone.c.project-id.internal",
-        "username": "gcp_user",
-        "cluster_port": 22,
-        "default_cores": 16,
-        "default_memory": "64GB",
-        "remote_work_dir": "/home/gcp_user/clustrix",
-        "package_manager": "conda",
-        "cost_monitoring": True,
-        "description": "GCP Compute Engine instance via SSH",
-    },
-    "Azure VM via SSH": {
-        "name": "Azure VM via SSH",
-        "cluster_type": "ssh",
-        "cluster_host": "vm-name.region.cloudapp.azure.com",
-        "username": "azureuser",
-        "cluster_port": 22,
-        "default_cores": 12,
-        "default_memory": "48GB",
-        "remote_work_dir": "/home/azureuser/clustrix",
-        "package_manager": "conda",
-        "cost_monitoring": True,
-        "description": "Azure Virtual Machine via SSH",
-    },
 }