新增角色管理、世界观设定、章节管理和AI工具调用功能

- 角色管理：CRUD API + 卡片网格UI，每个角色约200字描述
- 世界观设定：单篇长文编辑器，建议500字以上
- 章节管理：CRUD + 排序 API，左右分栏编辑器，单章5000字上限
- AI工具调用：支持工具审批流程和结构化工具调用
- 小说详情页新增章节、角色、世界观入口按钮

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/app/routers/chapters.py

@@ -0,0 +1,136 @@
+from datetime import datetime, timezone
+
+from fastapi import APIRouter, Depends, HTTPException
+from sqlmodel import Session, select, func
+
+from ..database import get_session
+from ..models import Novel, Chapter
+from ..schemas import (
+    ChapterCreate,
+    ChapterUpdate,
+    ChapterRead,
+    ChapterList,
+    ChapterReorder,
+)
+
+router = APIRouter(prefix="/api/novels/{novel_id}/chapters", tags=["chapters"])
+
+
+def _get_novel_or_404(novel_id: int, session: Session) -> Novel:
+    novel = session.get(Novel, novel_id)
+    if not novel:
+        raise HTTPException(status_code=404, detail="小说不存在")
+    return novel
+
+
+def _get_chapter_or_404(
+    chapter_id: int, novel_id: int, session: Session
+) -> Chapter:
+    chapter = session.get(Chapter, chapter_id)
+    if not chapter or chapter.novel_id != novel_id:
+        raise HTTPException(status_code=404, detail="章节不存在")
+    return chapter
+
+
+@router.get("", response_model=ChapterList)
+def list_chapters(
+    novel_id: int,
+    session: Session = Depends(get_session),
+):
+    _get_novel_or_404(novel_id, session)
+    total = session.exec(
+        select(func.count(Chapter.id)).where(Chapter.novel_id == novel_id)
+    ).one()
+    items = session.exec(
+        select(Chapter)
+        .where(Chapter.novel_id == novel_id)
+        .order_by(Chapter.sort_order)
+    ).all()
+    return ChapterList(
+        items=[ChapterRead.model_validate(c, from_attributes=True) for c in items],
+        total=total,
+    )
+
+
+@router.post("", response_model=ChapterRead, status_code=201)
+def create_chapter(
+    novel_id: int,
+    data: ChapterCreate,
+    session: Session = Depends(get_session),
+):
+    _get_novel_or_404(novel_id, session)
+    max_order = session.exec(
+        select(func.max(Chapter.sort_order)).where(Chapter.novel_id == novel_id)
+    ).one()
+    next_order = (max_order or 0) + 1
+
+    chapter = Chapter(novel_id=novel_id, sort_order=next_order, **data.model_dump())
+    session.add(chapter)
+    session.commit()
+    session.refresh(chapter)
+    return chapter
+
+
+@router.put("/reorder", response_model=ChapterList)
+def reorder_chapters(
+    novel_id: int,
+    data: ChapterReorder,
+    session: Session = Depends(get_session),
+):
+    _get_novel_or_404(novel_id, session)
+    now = datetime.now(timezone.utc)
+    for idx, cid in enumerate(data.ordered_ids):
+        chapter = _get_chapter_or_404(cid, novel_id, session)
+        chapter.sort_order = idx + 1
+        chapter.updated_at = now
+        session.add(chapter)
+    session.commit()
+
+    items = session.exec(
+        select(Chapter)
+        .where(Chapter.novel_id == novel_id)
+        .order_by(Chapter.sort_order)
+    ).all()
+    total = len(items)
+    return ChapterList(
+        items=[ChapterRead.model_validate(c, from_attributes=True) for c in items],
+        total=total,
+    )
+
+
+@router.get("/{chapter_id}", response_model=ChapterRead)
+def get_chapter(
+    novel_id: int,
+    chapter_id: int,
+    session: Session = Depends(get_session),
+):
+    return _get_chapter_or_404(chapter_id, novel_id, session)
+
+
+@router.patch("/{chapter_id}", response_model=ChapterRead)
+def update_chapter(
+    novel_id: int,
+    chapter_id: int,
+    data: ChapterUpdate,
+    session: Session = Depends(get_session),
+):
+    chapter = _get_chapter_or_404(chapter_id, novel_id, session)
+    update_data = data.model_dump(exclude_unset=True)
+    for key, value in update_data.items():
+        setattr(chapter, key, value)
+    chapter.updated_at = datetime.now(timezone.utc)
+    session.add(chapter)
+    session.commit()
+    session.refresh(chapter)
+    return chapter
+
+
+@router.delete("/{chapter_id}", status_code=204)
+def delete_chapter(
+    novel_id: int,
+    chapter_id: int,
+    session: Session = Depends(get_session),
+):
+    chapter = _get_chapter_or_404(chapter_id, novel_id, session)
+    session.delete(chapter)
+    session.commit()