feat(api): add public RESTful API with API key auth and documentation page

app/main.py

@@ -5,15 +5,16 @@ from fastapi.staticfiles import StaticFiles
 
 from app.config import UPLOAD_DIR
 from app.database import init_db
-from app.routers import web
+from app.routers import web, api
 
-app = FastAPI(title="Postcard Manager")
+app = FastAPI(title="Mailova 星笺")
 
 UPLOAD_DIR.mkdir(exist_ok=True)
 app.mount("/static", StaticFiles(directory=str(Path(__file__).resolve().parent / "static")), name="static")
 app.mount("/uploads", StaticFiles(directory=str(UPLOAD_DIR)), name="uploads")
 
 app.include_router(web.router)
+app.include_router(api.router)
 
 init_db()