Adds frontend build to Dockerfile

Adds Node.js and npm to the Docker image to allow building frontend assets during the Docker build process.

This ensures that the Go embed functionality works correctly by including the necessary frontend files in the built binary.

Author: KariHall619

Dockerfile

@@ -2,7 +2,7 @@
 FROM golang:1.24-alpine AS builder
 
 # Install build dependencies
-RUN apk add --no-cache git ca-certificates tzdata
+RUN apk add --no-cache git ca-certificates tzdata nodejs npm
 
 # Set working directory
 WORKDIR /app
@@ -13,6 +13,10 @@ COPY . .
 # Download dependencies (replace directive requires source to be present)
 RUN go mod download
 
+# Build frontend assets required for Go embed
+RUN npm ci --prefix frontend
+RUN npm run build --prefix frontend
+
 # Build the binary
 RUN CGO_ENABLED=0 GOOS=linux go build \
     -ldflags="-s -w" \