prepare fastapi root layout for server deployment

app/main.py

@@ -0,0 +1,36 @@
+from fastapi import FastAPI
+from fastapi.middleware.cors import CORSMiddleware
+
+from app.api import health
+from app.api.router import api_router
+from app.core.config import settings
+from app.core.errors import register_exception_handlers
+
+
+def create_app() -> FastAPI:
+    """应用工厂：创建 FastAPI 实例并挂载中间件、路由和异常处理器。"""
+    app = FastAPI(
+        title=settings.app_name,
+        debug=settings.app_debug,
+        version="0.1.0",
+        root_path=settings.app_root_path,
+        docs_url="/docs",
+        redoc_url="/redoc",
+    )
+
+    app.add_middleware(
+        CORSMiddleware,
+        allow_origins=settings.cors_allow_origins,
+        allow_origin_regex=settings.cors_allow_origin_regex or None,
+        allow_credentials=True,
+        allow_methods=["*"],
+        allow_headers=["*"],
+    )
+
+    app.include_router(health.router, prefix="/health", tags=["health"])
+    app.include_router(api_router, prefix=settings.api_v1_prefix)
+    register_exception_handlers(app)
+    return app
+
+
+app = create_app()