fix: remove go.sum from dockerfile as it is not present

Dockerfile

@@ -12,7 +12,7 @@ RUN npm run build
 FROM golang:1.24-alpine AS builder
 WORKDIR /app
 RUN apk add --no-cache git
-COPY go.mod go.sum ./
+COPY go.mod ./
 RUN go mod download
 COPY . .
 # Copy the built frontend from Step 1