feat: add config error handling on startup

Add error handling for configuration loading at application startup.
If the config file is missing or invalid, the app will exit with
a clear error message instead of crashing later.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

app/main.py

@@ -1,7 +1,21 @@
+import sys
+
 from fastapi import FastAPI, Request
 from fastapi.exceptions import RequestValidationError
 from fastapi.responses import JSONResponse
 
+from config.settings import load_settings
+
+# 加载配置文件，失败则退出
+try:
+    settings = load_settings()
+except FileNotFoundError as e:
+    print(f"配置文件错误: {e}")
+    sys.exit(1)
+except Exception as e:
+    print(f"加载配置失败: {e}")
+    sys.exit(1)
+
 from app.api.v1.location import router as location_router
 from app.api.v1.box import router as box_router
 from app.services.location_service import DuplicateLocationError