update:1.优化 AI 流式生成和进度显示系统 2.新增写作风格系统提示词支持 3.灵感模式功能增强,支持灵感重写 4.设置页面功能扩展，新增Gemini适配器 5.提示词模板系统优化，调整灵感模式提示词

backend/app/services/ai_providers/base_provider.py

@@ -0,0 +1,33 @@
+"""AI Provider 基类"""
+from abc import ABC, abstractmethod
+from typing import Any, AsyncGenerator, Dict, List, Optional
+
+
+class BaseAIProvider(ABC):
+    """AI 提供商抽象基类"""
+
+    @abstractmethod
+    async def generate(
+        self,
+        prompt: str,
+        model: str,
+        temperature: float,
+        max_tokens: int,
+        system_prompt: Optional[str] = None,
+        tools: Optional[List[Dict]] = None,
+        tool_choice: Optional[str] = None,
+    ) -> Dict[str, Any]:
+        """生成文本"""
+        pass
+
+    @abstractmethod
+    async def generate_stream(
+        self,
+        prompt: str,
+        model: str,
+        temperature: float,
+        max_tokens: int,
+        system_prompt: Optional[str] = None,
+    ) -> AsyncGenerator[str, None]:
+        """流式生成"""
+        pass