feat: AI改写功能集成角色数据 + UI优化

- 新增story_characters表和seed_characters.sql种子数据(27个角色)
- AI改写/续写功能注入角色信息(性别/年龄/外貌/性格)
- 首页UI下移避让微信退出按钮
- 个人中心页面布局重构

server/app/routers/drafts.py

@@ -10,11 +10,32 @@ from typing import List, Optional
 from datetime import datetime
 
 from app.database import get_db
-from app.models.story import Story, StoryDraft, DraftStatus
+from app.models.story import Story, StoryDraft, DraftStatus, StoryCharacter
 
 router = APIRouter(prefix="/drafts", tags=["草稿箱"])
 
 
+# ============ 辅助函数 ============
+
+async def get_story_characters(db: AsyncSession, story_id: int) -> List[dict]:
+    """获取故事的所有角色并转为字典列表"""
+    result = await db.execute(
+        select(StoryCharacter).where(StoryCharacter.story_id == story_id)
+    )
+    characters = result.scalars().all()
+    return [
+        {
+            "name": c.name,
+            "role_type": c.role_type,
+            "gender": c.gender,
+            "age_range": c.age_range,
+            "appearance": c.appearance,
+            "personality": c.personality
+        }
+        for c in characters
+    ]
+
+
 # ============ 请求/响应模型 ============
 
 class PathHistoryItem(BaseModel):
@@ -98,6 +119,9 @@ async def process_ai_rewrite(draft_id: int):
                 await db.commit()
                 return
             
+            # 获取故事角色
+            characters = await get_story_characters(db, story.id)
+            
             # 转换路径历史格式
             path_history = draft.path_history or []
             
@@ -107,7 +131,8 @@ async def process_ai_rewrite(draft_id: int):
                 story_category=story.category or "未知",
                 path_history=path_history,
                 current_content=draft.current_content or "",
-                user_prompt=draft.user_prompt
+                user_prompt=draft.user_prompt,
+                characters=characters
             )
             
             if ai_result and ai_result.get("nodes"):
@@ -171,6 +196,9 @@ async def process_ai_rewrite_ending(draft_id: int):
                 await db.commit()
                 return
             
+            # 获取故事角色
+            characters = await get_story_characters(db, story.id)
+            
             # 从草稿字段获取结局信息
             ending_name = draft.current_node_key or "未知结局"
             ending_content = draft.current_content or ""
@@ -181,7 +209,8 @@ async def process_ai_rewrite_ending(draft_id: int):
                 story_category=story.category or "未知",
                 ending_name=ending_name,
                 ending_content=ending_content,
-                user_prompt=draft.user_prompt
+                user_prompt=draft.user_prompt,
+                characters=characters
             )
             
             if ai_result and ai_result.get("content"):
@@ -266,6 +295,9 @@ async def process_ai_continue_ending(draft_id: int):
                 await db.commit()
                 return
             
+            # 获取故事角色
+            characters = await get_story_characters(db, story.id)
+            
             # 从草稿字段获取结局信息
             ending_name = draft.current_node_key or "未知结局"
             ending_content = draft.current_content or ""
@@ -276,7 +308,8 @@ async def process_ai_continue_ending(draft_id: int):
                 story_category=story.category or "未知",
                 ending_name=ending_name,
                 ending_content=ending_content,
-                user_prompt=draft.user_prompt
+                user_prompt=draft.user_prompt,
+                characters=characters
             )
             
             if ai_result and ai_result.get("nodes"):