chore: Update Node.js version to 24.15.0 in CI and Dockerfile for consistency

Co-authored-by: Copilot <copilot@github.com>

.github/workflows/test.yml

@@ -12,7 +12,7 @@ jobs:
     
     strategy:
       matrix:
-        node-version: [24.x]
+        node-version: [24.15.0]
 
     steps:
       - name: Checkout code

backend/Dockerfile

@@ -1,21 +1,22 @@
 # Byggas från projektets rot: docker build -f backend/Dockerfile -t recipe-importer-api:local .
 
 # Stage 1: Bygg applikationen
-FROM node:22-alpine AS builder
+FROM node:24.15.0-alpine AS builder
 WORKDIR /app
 
 # Kopiera backend-filer
 COPY backend/package.json ./
+COPY backend/package-lock.json ./
 COPY backend/src ./src
 COPY backend/tsconfig.json ./
 COPY backend/nest-cli.json ./
 
-# Köra npm install
+# Köra npm ci för reproducerbara builds
-RUN npm install
+RUN npm ci
 RUN npm run build
 
 # Stage 2: Kör applikationen
-FROM node:22-alpine AS runner
+FROM node:24.15.0-alpine AS runner
 WORKDIR /app
 ENV NODE_ENV=production