perf: SQLite WAL + 复合索引 + GZip + scheduler jitter + 构建缓存

backend/app/main.py

@@ -5,6 +5,7 @@ from pathlib import Path
 
 from fastapi import FastAPI, HTTPException
 from fastapi.middleware.cors import CORSMiddleware
+from fastapi.middleware.gzip import GZipMiddleware
 from fastapi.staticfiles import StaticFiles
 from fastapi.responses import FileResponse
 
@@ -88,6 +89,7 @@ app.add_middleware(
     allow_methods=["*"],
     allow_headers=["*"],
 )
+app.add_middleware(GZipMiddleware, minimum_size=1024)
 
 # API routers
 app.include_router(auth.router)