Add FastAPI backend with agent system

backend/app/schemas/settings.py

@@ -0,0 +1,58 @@
+from pydantic import BaseModel, Field
+from typing import Optional, Literal, List
+from app.schemas.auth import UserOut
+
+# LLM Provider 类型
+LLMProviderType = Literal["openai", "claude", "ollama", "deepseek", "custom"]
+LLMType = Literal["chat", "vlm", "embedding", "rerank"]
+
+
+# 单个模型配置
+class LLMModelConfig(BaseModel):
+    name: str = ""  # 模型名称/别名，用于标识
+    provider: LLMProviderType = "openai"
+    model: str = ""
+    base_url: str = ""
+    api_key: str = ""
+    enabled: bool = True  # 是否启用
+
+
+# LLM 配置输入 - 每种类型支持多个模型
+class LLMConfigIn(BaseModel):
+    chat: Optional[List[LLMModelConfig]] = []
+    vlm: Optional[List[LLMModelConfig]] = []
+    embedding: Optional[List[LLMModelConfig]] = []
+    rerank: Optional[List[LLMModelConfig]] = []
+
+
+# 定时任务配置
+class SchedulerConfigIn(BaseModel):
+    daily_plan_time: Optional[str] = "08:00"
+    forum_scan_interval_minutes: Optional[int] = 30
+    todo_ai_generate_time: Optional[str] = "08:00"
+    enabled: Optional[bool] = True
+
+
+# 用户资料更新
+class ProfileUpdateIn(BaseModel):
+    full_name: Optional[str] = Field(None, min_length=2, max_length=50)
+    password: Optional[str] = Field(None, min_length=8)
+    current_password: Optional[str] = None
+
+
+# 完整设置输出
+class SettingsOut(BaseModel):
+    profile: UserOut
+    llm_config: Optional[dict] = None
+    scheduler_config: Optional[dict] = None
+
+    model_config = {"from_attributes": True}
+
+
+# 测试 LLM 连接请求
+class LLMTestIn(BaseModel):
+    type: LLMType
+    provider: LLMProviderType
+    model: str
+    base_url: str
+    api_key: str