runtime-rs: refine ShareFs abstraction with lifecycle and Nydus traits

Refactor the `ShareFs` trait to improve modularity and support
standalone Nydus mode:

(1) Added `stop()` method to manage daemon teardown.
(2) Introduced a dedicated trait for Nydus-specific data-plane
operations.

This refactoring cleans up the `ShareFs` trait by consolidating
daemon lifecycle handling and isolating Nydus-specific extensions,
paving the way for cleaner standalone Nydus implementation.

Signed-off-by: Alex Lyn <alex.lyn@antgroup.com>

src/runtime-rs/crates/resource/src/share_fs/mod.rs

@@ -69,6 +69,33 @@ pub trait ShareFs: Send + Sync {
     ) -> Result<()>;
     async fn get_storages(&self) -> Result<Vec<Storage>>;
     fn mounted_info_set(&self) -> Arc<Mutex<HashMap<String, MountedInfo>>>;
+
+    /// Stop the share fs daemon process (e.g., virtiofsd, nydusd).
+    /// Called during sandbox cleanup before cleaning up mounts.
+    /// Default implementation does nothing for inline modes that don't manage external daemons.
+    async fn stop(&self) -> Result<()> {
+        Ok(())
+    }
+}
+
+/// Trait for nydus-specific data-plane operations (standalone nydusd mode).
+/// This trait is implemented by ShareVirtioFsNydus and provides operations
+/// that are specific to the nydusd daemon's rafs mount capabilities.
+#[async_trait]
+pub trait NydusShareFs: Send + Sync {
+    /// Mount rafs with nydusd native overlay support.
+    /// Returns the mount point path within the nydusd namespace.
+    async fn mount_rafs(
+        &self,
+        cid: &str,
+        rafs_meta: &str,
+        config: &str,
+        overlay_config: &str,
+    ) -> Result<String>;
+
+    /// Umount rafs from nydusd.
+    /// Called during container cleanup.
+    async fn umount_rafs(&self, mountpoint: &str) -> Result<()>;
 }
 
 #[derive(Debug, Clone)]

src/runtime-rs/crates/resource/src/share_fs/share_virtio_fs_standalone.rs

@@ -256,4 +256,10 @@ impl ShareFs for ShareVirtioFsStandalone {
     fn mounted_info_set(&self) -> Arc<Mutex<HashMap<String, MountedInfo>>> {
         self.mounted_info_set.clone()
     }
+
+    async fn stop(&self) -> Result<()> {
+        self.shutdown_virtiofsd()
+            .await
+            .context("failed to stop virtiofsd daemon")
+    }
 }