Add CI to build/push Docker image, switch compose to pull it

Matches the etsy-finance-tracker pattern: Forgejo Actions builds and
pushes the image on every push to main, and docker-compose.yml now
pulls that image instead of building from source on the deploy host.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

.forgejo/workflows/docker-build.yml

@@ -0,0 +1,44 @@
+name: Build and Push Docker Image
+
+on:
+  push:
+    branches: [main]
+
+defaults:
+  run:
+    shell: sh
+
+jobs:
+  build-and-push:
+    # Runner offers ubuntu-latest; the label only selects the runner. The job
+    # overrides the image below with docker:cli and mounts the host socket.
+    runs-on: ubuntu-latest
+    # Run the job in a Docker-CLI container. act_runner already auto-mounts the
+    # host Docker socket (OrbStack), so `docker` reaches the host daemon — don't
+    # mount it again here or Docker errors with "Duplicate mount point".
+    container:
+      image: docker:cli
+    steps:
+      - name: Install git
+        run: apk add --no-cache git
+
+      - name: Checkout
+        run: |
+          git config --global --add safe.directory '*'
+          git init -q .
+          git remote add origin "https://${{ github.actor }}:${{ secrets.GITHUB_TOKEN }}@git.plexultra.com/${{ github.repository }}.git" \
+            || git remote set-url origin "https://${{ github.actor }}:${{ secrets.GITHUB_TOKEN }}@git.plexultra.com/${{ github.repository }}.git"
+          git fetch --depth 1 origin "${{ github.ref_name }}"
+          git checkout -q -f FETCH_HEAD
+
+      # Uses a Forgejo token with write:package scope (the auto GITHUB_TOKEN
+      # can't write packages — push fails with 'unauthorized: reqPackageAccess')
+      - name: Log in to Forgejo container registry
+        run: echo "${{ secrets.REGISTRY_TOKEN }}" | docker login git.plexultra.com -u "${{ github.actor }}" --password-stdin
+
+      - name: Build and push image
+        run: |
+          IMAGE=git.plexultra.com/${{ github.repository }}
+          docker build -t "$IMAGE:main" -t "$IMAGE:${{ github.sha }}" .
+          docker push "$IMAGE:main"
+          docker push "$IMAGE:${{ github.sha }}"

docker-compose.yml

@@ -1,6 +1,6 @@
 services:
   power-compare:
-    build: .
+    image: git.plexultra.com/dlawler489/power-compare:main
     ports:
       - "8000:8000"
     env_file: