fix: add grade column to tables.py + middleware error alerting

1. tables.py: members table was missing grade column definition
   (migration 003 added it to DB but tables.py was not updated)

2. Slack alerts: Starlette ServerErrorMiddleware catches exceptions
   before FastAPI exception handlers. Add ErrorAlertMiddleware that
   logs to root logger (→ SlackHandler) before re-raising.

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

Author: ImTotem

src/bcsd_api/exception/handlers.py

@@ -2,22 +2,36 @@
 
 from fastapi import FastAPI, Request
 from fastapi.responses import JSONResponse
+from starlette.middleware.base import BaseHTTPMiddleware
 
 from .base import AppException
 
-logger = logging.getLogger("bcsd_api.error")
+root_logger = logging.getLogger()
 
 
 def register_handlers(app: FastAPI) -> None:
+    app.add_middleware(ErrorAlertMiddleware)
+
     @app.exception_handler(AppException)
     async def _handle(request: Request, exc: AppException) -> JSONResponse:
         body = {"error_code": exc.error_code, "message": exc.message}
         return JSONResponse(status_code=exc.status_code, content=body)
 
     @app.exception_handler(Exception)
     async def _unhandled(request: Request, exc: Exception) -> JSONResponse:
-        logging.getLogger().error(
+        root_logger.error(
             "%s %s: %s", request.method, request.url.path, exc, exc_info=exc,
         )
         body = {"error_code": "INTERNAL_ERROR", "message": "internal server error"}
         return JSONResponse(status_code=500, content=body)
+
+
+class ErrorAlertMiddleware(BaseHTTPMiddleware):
+    async def dispatch(self, request, call_next):
+        try:
+            return await call_next(request)
+        except Exception as exc:
+            root_logger.error(
+                "%s %s: %s", request.method, request.url.path, exc, exc_info=exc,
+            )
+            raise

src/bcsd_api/tables.py

@@ -17,6 +17,7 @@
     Column("role", String),
     Column("join_date", String),
     Column("payment_status", String, server_default="미납"),
+    Column("grade", String),
     Column("last_updated", String),
 )