fix: cast test objects to Base types for union type compatibility

- Cast notification objects to NotificationBase in mcp.test.ts
- Cast request/result objects to Base types in protocol.test.ts
- Ensures tests compile with union type changes

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Co-Authored-By: Claude <noreply@anthropic.com>

Author: ochafik

test/shared/protocol.test.ts

@@ -4911,7 +4911,7 @@ describe('Error handling for missing resolvers', () => {
             await protocol.connect(transport);
 
             // Create a task
-            const task = await taskStore.createTask({ ttl: 60000 }, 1, { method: 'test', params: {} } as RequestBase);
+            const task = await taskStore.createTask({ ttl: 60000 }, 1, { method: 'test', params: {} } as unknown as Request);
 
             // Enqueue a response message without a corresponding resolver
             await taskMessageQueue.enqueue(task.taskId, {