Implement SMB Oplocks Phase 1-2

Phase 1: Data structures
- Add oplock_level and share_access fields to Open struct
- Update Open::new() signature with new parameters
- Update handlers/create.rs to pass oplock params

Phase 2: OplockManager
- Create oplock.rs with OplockManager struct
- OplockEntry for tracking per-client oplock state
- can_grant() - check ShareAccess compatibility
- register() / unregister() - lifecycle management
- break_oplock() - generate OPLOCK_BREAK_NOTIFICATION
- Add OplockManager to ServerState
- Add Hash trait to SmbPath for HashMap key

All 229 tests pass.

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

@@ -153,6 +153,10 @@ pub async fn handle(
     // Allocate FileId, register Open.
     let tree = tree_arc.write().await;
     let file_id = tree.alloc_file_id();
+    
+    // Phase 4: Oplock support - determine oplock level
+    let granted_oplock = 0; // Phase 1 placeholder (will be dynamic in Phase 4)
+    
     let open = Open::new(
         file_id,
         handle,
@@ -160,6 +164,8 @@ pub async fn handle(
         path,
         info.is_directory,
         delete_on_close,
+        granted_oplock, // oplock_level
+        req.share_access, // share_access
     );
     let open_arc = Arc::new(tokio::sync::RwLock::new(open));
     tree.opens.write().await.insert(file_id, open_arc);
@@ -172,7 +178,7 @@ pub async fn handle(
     };
     let resp = CreateResponse {
         structure_size: 89,
-        oplock_level: 0,
+        oplock_level: granted_oplock, // Phase 4: will be dynamic
         flags: 0,
         create_action,
         creation_time: info.creation_time,