修復 Part.from_text() API 使用錯誤

- 在 Part.from_text() 中加入必要的 text= 關鍵字參數
- 解決 'Part.from_text() takes 1 positional argument but 2 were given' 錯誤
- 符合最新的 Google GenAI Python SDK API 規範

🤖 Generated with [Claude Code](https://claude.ai/code)

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

app.py

@@ -78,7 +78,7 @@ def analyze_food_calories(image):
             types.Content(
                 role="user",
                 parts=[
-                    types.Part.from_text(prompt),
+                    types.Part.from_text(text=prompt),
                     types.Part.from_bytes(
                         data=img_byte_arr,
                         mime_type="image/png"