feat: FastAPI skeleton with config, database, health endpoint

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

backend/app/main.py

@@ -0,0 +1,34 @@
+"""FastAPI 应用入口。"""
+from contextlib import asynccontextmanager
+from fastapi import FastAPI
+from fastapi.middleware.cors import CORSMiddleware
+
+from app.database import engine, Base
+
+
+@asynccontextmanager
+async def lifespan(app: FastAPI):
+    async with engine.begin() as conn:
+        await conn.run_sync(Base.metadata.create_all)
+    yield
+    await engine.dispose()
+
+
+app = FastAPI(
+    title="Hive Manage v3",
+    version="0.1.0",
+    lifespan=lifespan,
+)
+
+app.add_middleware(
+    CORSMiddleware,
+    allow_origins=["*"],
+    allow_credentials=True,
+    allow_methods=["*"],
+    allow_headers=["*"],
+)
+
+
+@app.get("/api/v1/health")
+async def health_check():
+    return {"status": "ok"}