feat(cluster): add shard healing, drive health heartbeats, and clustered policy directory support

rust/src/storage.rs

@@ -811,14 +811,18 @@ impl StorageBackend {
     pub fn policies_dir(&self) -> std::path::PathBuf {
         match self {
             StorageBackend::Standalone(fs) => fs.policies_dir(),
-            StorageBackend::Clustered(_) => PathBuf::from(".policies"), // TODO: proper policies in cluster mode
+            StorageBackend::Clustered(ds) => ds.policies_dir(),
         }
     }
 
     pub async fn initialize(&self) -> Result<()> {
         match self {
             StorageBackend::Standalone(fs) => fs.initialize().await,
-            StorageBackend::Clustered(_) => Ok(()), // Cluster init happens separately
+            StorageBackend::Clustered(ds) => {
+                // Ensure policies directory exists
+                tokio::fs::create_dir_all(ds.policies_dir()).await?;
+                Ok(())
+            }
         }
     }