Remove gemini-stream.ts (#84)

This module is no longer needed and the types can be provided from types.

packages/cli/src/ui/hooks/useGeminiStream.ts

@@ -30,11 +30,11 @@ import {
   type Part,
 } from '@google/genai';
 import {
+  StreamingState,
   HistoryItem,
   IndividualToolCallDisplay,
   ToolCallStatus,
 } from '../types.js';
-import { StreamingState } from '../../core/gemini-stream.js';
 import { toolRegistry } from '../../tools/tool-registry.js';
 
 const addHistoryItem = (