新增前后端AI聊天模块，包括流式对话、配置管理和UI组件优化。

backend/app/schemas.py

@@ -0,0 +1,105 @@
+from datetime import datetime
+
+from pydantic import BaseModel, Field
+
+
+class NovelCreate(BaseModel):
+    title: str = Field(min_length=1, max_length=200)
+    description: str = Field(default="", max_length=2000)
+
+
+class NovelUpdate(BaseModel):
+    title: str | None = Field(default=None, min_length=1, max_length=200)
+    description: str | None = Field(default=None, max_length=2000)
+
+
+class NovelRead(BaseModel):
+    id: int
+    title: str
+    description: str
+    created_at: datetime
+    updated_at: datetime
+
+
+class NovelList(BaseModel):
+    items: list[NovelRead]
+    total: int
+
+
+# ── 大纲 ──
+
+
+class OutlineCreate(BaseModel):
+    summary: str = Field(min_length=1, max_length=200)
+    detail: str = Field(default="", max_length=1000)
+
+
+class OutlineUpdate(BaseModel):
+    summary: str | None = Field(default=None, min_length=1, max_length=200)
+    detail: str | None = Field(default=None, max_length=1000)
+    sort_order: int | None = None
+
+
+class OutlineRead(BaseModel):
+    id: int
+    novel_id: int
+    sort_order: int
+    summary: str
+    detail: str
+    created_at: datetime
+    updated_at: datetime
+
+
+class OutlineList(BaseModel):
+    items: list[OutlineRead]
+    total: int
+
+
+class OutlineReorder(BaseModel):
+    """排序请求：按顺序传入大纲id列表"""
+    ordered_ids: list[int]
+
+
+# ── AI配置 ──
+
+
+class AIConfigSave(BaseModel):
+    provider: str = Field(default="openai")
+    base_url: str = Field(default="https://api.openai.com/v1")
+    api_key: str = Field(min_length=1)
+    model: str = Field(default="gpt-4o")
+
+
+class AIConfigRead(BaseModel):
+    id: int
+    provider: str
+    base_url: str
+    api_key_masked: str  # 脱敏后的key
+    model: str
+    updated_at: datetime
+
+
+# ── 聊天 ──
+
+
+class ChatMessageInput(BaseModel):
+    role: str
+    content: str
+
+
+class ChatRequest(BaseModel):
+    messages: list[ChatMessageInput]
+    novel_id: int | None = None
+
+
+class ChatMessageRead(BaseModel):
+    id: int
+    novel_id: int | None
+    role: str
+    content: str
+    created_at: datetime
+
+
+class ChatMessageList(BaseModel):
+    items: list[ChatMessageRead]
+    total: int