feat: TenantRuntime/Registry——每租户懒建 engine(WAL/pool2)+文件加载器+站点解析

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

app/main.py

@@ -2,11 +2,10 @@ from contextlib import asynccontextmanager
 
 from fastapi import FastAPI
 from fastapi.staticfiles import StaticFiles
-from sqlalchemy import text
 from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker, create_async_engine
 
 from app.engine.config import settings, ensure_dirs, STATIC_DIR
-from app.engine.models import Base
+from app.engine.models import ensure_schema
 
 
 # 后台推送任务的独立连接写结果可能撞上 SMTP 窗口内持有的写锁,默认 5s
@@ -16,28 +15,10 @@ engine = create_async_engine(settings.DATABASE_URL, echo=settings.APP_DEBUG,
 async_session = async_sessionmaker(engine, class_=AsyncSession, expire_on_commit=False)
 
 
-async def _migrate(conn):
-    result = await conn.execute(text("PRAGMA table_info(conversations)"))
-    columns = {row[1] for row in result}
-    if "page_token" not in columns:
-        await conn.execute(text(
-            "ALTER TABLE conversations ADD COLUMN page_token VARCHAR(64)"
-        ))
-
-    result = await conn.execute(text("PRAGMA table_info(evaluations)"))
-    columns = {row[1] for row in result}
-    if "correction_count" not in columns:
-        await conn.execute(text(
-            "ALTER TABLE evaluations ADD COLUMN correction_count INTEGER DEFAULT 0"
-        ))
-
-
 @asynccontextmanager
 async def lifespan(app: FastAPI):
     ensure_dirs()
-    async with engine.begin() as conn:
-        await conn.run_sync(Base.metadata.create_all)
-        await _migrate(conn)
+    await ensure_schema(engine)
     # 询盘推送(设计 8.2): 清扫崩溃遗留的 stale pending → failed
     # 函数内导入: lead_push_service 顶部 from app.main import async_session,
     # 顶层互相导入会循环