Add READ handler oplock break (Phase 5.5)

- Trigger oplock break before read if conflicting opens exist
- Use granted_access from Open struct
- Send notifications via notification_tx channel
- Fix WRITE handler granted_access source (from Tree)

All 229 tests pass.

vendor/smb-server/src/handlers/write.rs

@@ -48,11 +48,17 @@ pub async fn handle(
         (open.last_path.clone(), open.share_access)
     };
     
+    // Get granted_access from tree
+    let granted_access = {
+        let tree = tree_arc.read().await;
+        tree.granted_access
+    };
+    
     // Trigger oplock break for conflicting clients
     let notifications = server.oplock_manager.break_oplock(
         &path,
         share_access,
-        granted,
+        granted_access,
     ).await;
     
     // Send notifications to affected clients