Rename production image tag to 'production' and add CI workflow for staging branch

.github/workflows/docker-image-staging.yml

@@ -0,0 +1,18 @@
+name: Docker Image CI (Staging)
+
+on:
+  push:
+    branches: ['staging']
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+      - name: Build and publish a Docker image for ${{ github.repository }}
+        uses: macbre/push-to-ghcr@master
+        with:
+          image_name: ${{ github.repository }}
+          github_token: ${{ secrets.GITHUB_TOKEN }}
+          image_tag: staging

.github/workflows/docker-image.yml

@@ -2,18 +2,17 @@ name: Docker Image CI
 
 on:
   push:
-    branches: [ "main" ]
+    branches: ['main']
 
 jobs:
-
   build:
-
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v4
-    - name: Build and publish a Docker image for ${{ github.repository }}
-      uses: macbre/push-to-ghcr@master
-      with:
-        image_name: ${{ github.repository }}
-        github_token: ${{ secrets.GITHUB_TOKEN }}
+      - uses: actions/checkout@v4
+      - name: Build and publish a Docker image for ${{ github.repository }}
+        uses: macbre/push-to-ghcr@master
+        with:
+          image_name: ${{ github.repository }}
+          github_token: ${{ secrets.GITHUB_TOKEN }}
+          image_tag: production

README.md

@@ -57,10 +57,10 @@ services:
     env_file:
       - .env
     pull_policy: always
-    image: ghcr.io/hackclub/construct:latest
+    image: ghcr.io/hackclub/construct:production
 networks: {}
 volumes:
   constructdb:
 ```
 
-Use the `staging` image tag instead of `latest` for the staging environment.
+Use the `staging` image tag instead of `production` for the staging environment.