Allow relative volume paths for k8s-kind deployments

For k8s-kind, relative paths (e.g., ./data/rpc-config) are resolved to
$DEPLOYMENT_DIR/path by _make_absolute_host_path() during kind config
generation. This provides Docker Host persistence that survives cluster
restarts.

Previously, validation threw an exception before paths could be resolved,
making it impossible to use relative paths for persistent storage.

Changes:
- deployment_create.py: Skip relative path check for k8s-kind
- cluster_info.py: Allow relative paths to reach PV generation
- docs/deployment_patterns.md: Document volume persistence patterns

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

stack_orchestrator/deploy/k8s/cluster_info.py

@@ -352,11 +352,15 @@ class ClusterInfo:
                 continue
 
             if not os.path.isabs(volume_path):
-                print(
-                    f"WARNING: {volume_name}:{volume_path} is not absolute, "
-                    "cannot bind volume."
-                )
-                continue
+                # For k8s-kind, allow relative paths:
+                # - PV uses /mnt/{volume_name} (path inside kind node)
+                # - extraMounts resolve the relative path to Docker Host
+                if not self.spec.is_kind_deployment():
+                    print(
+                        f"WARNING: {volume_name}:{volume_path} is not absolute, "
+                        "cannot bind volume."
+                    )
+                    continue
 
             if self.spec.is_kind_deployment():
                 host_path = client.V1HostPathVolumeSource(