Fix backend Containerfile

Signed-off-by: Asai Neko <sugar@sne.moe>

container/backend.Containerfile

@@ -2,6 +2,7 @@ FROM docker.io/golang:1.25.5-alpine AS backend-build
 WORKDIR /app
 COPY . /app
 RUN go mod tidy && \
+    go generate . \
     go build -o /app/nixcn-cms
 
 FROM docker.io/alpine:3.23