引入二级大纲功能，新增父子节点关系及子节点排序，同时调整API与UI以支持嵌套大纲管理

backend/app/schemas.py

@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 from datetime import datetime
 
 from pydantic import BaseModel, Field
@@ -32,6 +34,7 @@ class NovelList(BaseModel):
 class OutlineCreate(BaseModel):
     summary: str = Field(min_length=1, max_length=200)
     detail: str = Field(default="", max_length=1000)
+    parent_id: int | None = None
 
 
 class OutlineUpdate(BaseModel):
@@ -43,9 +46,11 @@ class OutlineUpdate(BaseModel):
 class OutlineRead(BaseModel):
     id: int
     novel_id: int
+    parent_id: int | None = None
     sort_order: int
     summary: str
     detail: str
+    children: list[OutlineRead] = []
     created_at: datetime
     updated_at: datetime
 
@@ -175,6 +180,7 @@ class ChatRequest(BaseModel):
     novel_id: int | None = None
     page_context: str | None = None      # 用户当前所在页面，如 "大纲页" "世界观页"
     tools_enabled: bool = True            # 是否启用工具调用
+    auto_approve_tools: bool = False      # 是否自动执行工具（无需人工审批）
     # 工具审批续传
     pending_tool_calls: list[PendingToolCall] | None = None
     assistant_text: str | None = None     # LLM 在工具调用前输出的文本
@@ -191,3 +197,7 @@ class ChatMessageRead(BaseModel):
 class ChatMessageList(BaseModel):
     items: list[ChatMessageRead]
     total: int
+
+
+# 解决 OutlineRead 自引用
+OutlineRead.model_rebuild()