feat: 提示词和 AI 参数移至数据库管理

- AiSetting 模型新增 6 个提示词字段 + 3 个阶段温度字段
- main.py 迁移逻辑改为检测 ai_settings 表的新字段并填充默认值
- generate.py 从数据库读取生成提示词，去掉硬编码
- optimizer 从 API 读取各阶段提示词和温度，删除 prompts.py
- crawler 从 API 读取提取/改写提示词和温度，删除 prompts.py
- settings/active 端点去掉 token 认证（供爬虫/优化器使用）
- 后台设置页新增提示词编辑区和温度调节控件
- 新增 _ensure_default_settings 自动创建默认配置

api/app/schemas/setting.py

@@ -1,4 +1,4 @@
-from pydantic import BaseModel, ConfigDict, Field
+from pydantic import BaseModel, Field
 
 
 class AiSettingBase(BaseModel):
@@ -8,6 +8,20 @@ class AiSettingBase(BaseModel):
     model_name: str = Field(default="nvidia/llama-3.1-nemotron-70b-instruct")
     temperature: float = Field(default=0.7, ge=0, le=2)
     max_tokens: int = Field(default=2048, ge=1)
+
+    # 提示词
+    generate_prompt: str = Field(default="")
+    optimizer_quality_prompt: str = Field(default="")
+    optimizer_polish_prompt: str = Field(default="")
+    optimizer_evaluate_prompt: str = Field(default="")
+    crawler_extract_prompt: str = Field(default="")
+    crawler_rewrite_prompt: str = Field(default="")
+
+    # 优化器各阶段温度
+    optimizer_quality_temperature: float = Field(default=0.3, ge=0, le=2)
+    optimizer_polish_temperature: float = Field(default=0.8, ge=0, le=2)
+    optimizer_evaluate_temperature: float = Field(default=0.3, ge=0, le=2)
+
     crawl_enabled: bool = Field(default=False)
     crawl_keywords: str = Field(default="")
     max_pages_per_run: int = Field(default=3, ge=1)