feat: initial project structure

- Add FastAPI app with paper browsing UI and REST API
- Add crawler service and database models
- Add scripts for DB init and manual crawl
- Add docs (api-and-ui, data-model, services)
- Add requirements and project config

app/main.py

@@ -0,0 +1,59 @@
+"""FastAPI 应用入口。"""
+
+import logging
+import os
+
+from fastapi import FastAPI
+from fastapi.staticfiles import StaticFiles
+
+from app.config import settings
+from app.database import engine
+from app.models import init_db
+from app.routes.pages import router as pages_router
+
+logging.basicConfig(
+    level=logging.DEBUG if settings.APP_DEBUG else logging.INFO,
+    format="%(asctime)s [%(levelname)s] %(name)s: %(message)s",
+)
+logger = logging.getLogger(__name__)
+
+
+def create_app() -> FastAPI:
+    app = FastAPI(
+        title="HF Daily Papers",
+        description="HuggingFace Daily Papers — 中文论文导览站",
+        version="0.1.0",
+    )
+
+    # 确保数据目录存在
+    os.makedirs(settings.db_path.parent, exist_ok=True)
+
+    # 初始化数据库
+    init_db(engine)
+    logger.info("Database initialized at %s", settings.db_path)
+
+    # 安全警告
+    if settings.ADMIN_TOKEN == "change-me":
+        logger.warning("⚠️  ADMIN_TOKEN is the default value 'change-me'. Please change it in .env!")
+
+    # 静态文件
+    app.mount("/static", StaticFiles(directory="app/static"), name="static")
+
+    # 路由
+    app.include_router(pages_router)
+
+    return app
+
+
+app = create_app()
+
+
+if __name__ == "__main__":
+    import uvicorn
+
+    uvicorn.run(
+        "app.main:app",
+        host=settings.APP_HOST,
+        port=settings.APP_PORT,
+        reload=settings.APP_DEBUG,
+    )