fix: create NamespaceConfig resource after writing resolv.conf file

Moved NamespaceConfig::create() to after the resolv.conf file is written
to ensure the file exists before the resource tracks it for cleanup.

Author: ammario

src/jail/linux/mod.rs

@@ -431,11 +431,6 @@ impl LinuxJail {
             .with_context(|| format!("Failed to create directory: {}", netns_namespace_dir))?;
         debug!("Created directory: {}", netns_namespace_dir);
 
-        // Create namespace config resource
-        self.namespace_config = Some(ManagedResource::<NamespaceConfig>::create(
-            &self.config.jail_id,
-        )?);
-
         // Write custom resolv.conf that will be bind-mounted into the namespace
         // Point directly to the host's veth IP where our DNS server listens
         let resolv_conf_path = format!("{}/resolv.conf", netns_namespace_dir);
@@ -459,6 +454,12 @@ nameserver {}\n",
             anyhow::bail!("Failed to create resolv.conf at {}", resolv_conf_path);
         }
 
+        // Create namespace config resource for cleanup tracking
+        // IMPORTANT: Create this AFTER writing resolv.conf to ensure the file exists
+        self.namespace_config = Some(ManagedResource::<NamespaceConfig>::create(
+            &self.config.jail_id,
+        )?);
+
         Ok(())
     }