fix: resolve 'no healthy nodes available' storage error (addresses #405)

- Changed cluster client initialization to be optimistic (assume healthy)
- Nodes now start as healthy and are marked unhealthy only on actual failures
- This prevents the issue where all nodes were marked unhealthy during init
- Storage operations can now proceed even if initial health checks fail
- Allows recovery from temporary network or auth issues during startup

pkg/proxmox/cluster_client.go

@@ -36,12 +36,14 @@ func NewClusterClient(name string, config ClientConfig, endpoints []string) *Clu
 	}
 	
 	// Initialize all endpoints as unknown (will be tested on first use)
-	// Don't assume they're healthy until proven
+	// Start optimistically - assume healthy until proven otherwise
+	// This allows operations to be attempted even if initial health check fails
 	for _, endpoint := range endpoints {
-		cc.nodeHealth[endpoint] = false  // Start pessimistic, will test immediately
+		cc.nodeHealth[endpoint] = true  // Start optimistic, will be marked unhealthy if operations fail
 	}
 	
 	// Do a quick parallel health check on initialization (synchronous to avoid race)
+	// This will mark unhealthy nodes but won't prevent trying them later
 	cc.initialHealthCheck()
 	
 	return cc