ci: build & publish fork Docker image to GHCR

Triggered on every push to feat/group-member-add-mode. Produces:
  ghcr.io/hassankaid/evolution-api:member-add-mode
  ghcr.io/hassankaid/evolution-api:sha-<commit>

Allows users running self-hosted Evolution to swap their Docker image
to this fork while keeping all their state (sessions, DB, Redis)
untouched, until the upstream PR #2525 is merged.

Author: hassankaid

.github/workflows/publish-fork-image.yml

@@ -0,0 +1,48 @@
+name: Publish fork Docker image
+
+on:
+  push:
+    branches:
+      - 'feat/group-member-add-mode'
+  workflow_dispatch:
+
+permissions:
+  contents: read
+  packages: write
+
+jobs:
+  build-and-push:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v3
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Log in to GHCR
+        uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Compute lowercase repo
+        id: vars
+        run: echo "repo=$(echo '${{ github.repository }}' | tr '[:upper:]' '[:lower:]')" >> "$GITHUB_OUTPUT"
+
+      - name: Build and push
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          file: ./Dockerfile
+          push: true
+          platforms: linux/amd64
+          tags: |
+            ghcr.io/${{ steps.vars.outputs.repo }}:member-add-mode
+            ghcr.io/${{ steps.vars.outputs.repo }}:sha-${{ github.sha }}
+          cache-from: type=gha
+          cache-to: type=gha,mode=max