👷(CI) add GHCR workflow for forked repo testing

Add workflow_dispatch-triggered workflow that builds and pushes images
to GitHub Container Registry (ghcr.io). This allows forked repositories
to build their own images for testing without requiring Docker Hub
credentials.

Images are tagged with branch names, semver tags, and commit SHA for
easy testing of specific builds.

Signed-off-by: dtinth on MBP M1 <dtinth@spacet.me>

.github/workflows/ghcr.yml

@@ -0,0 +1,157 @@
+name: Build and Push to GHCR
+run-name: Build and Push to GHCR
+
+on:
+  workflow_dispatch:
+  push:
+    branches:
+      - 'main'
+    tags:
+      - 'v*'
+
+env:
+  DOCKER_USER: 1001:127
+  REGISTRY: ghcr.io
+
+jobs:
+  build-and-push-backend:
+    runs-on: ubuntu-latest
+    if: github.event.repository.fork == true
+    permissions:
+      contents: read
+      packages: write
+    steps:
+      -
+        name: Checkout repository
+        uses: actions/checkout@v4
+      -
+        name: Docker meta
+        id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: ${{ env.REGISTRY }}/${{ github.repository }}/backend
+          tags: |
+            type=ref,event=branch
+            type=ref,event=pr
+            type=semver,pattern={{version}}
+            type=semver,pattern={{major}}.{{minor}}
+            type=sha
+      -
+        name: Login to GHCR
+        uses: docker/login-action@v3
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+      -
+        name: Build and push
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          target: backend-production
+          build-args: DOCKER_USER=${{ env.DOCKER_USER }}:-1000
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}
+      -
+        name: Cleanup Docker after build
+        if: always()
+        run: |
+          docker system prune -af
+          docker volume prune -f
+
+  build-and-push-frontend:
+    runs-on: ubuntu-latest
+    if: github.event.repository.fork == true
+    permissions:
+      contents: read
+      packages: write
+    steps:
+      -
+        name: Checkout repository
+        uses: actions/checkout@v4
+      -
+        name: Docker meta
+        id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: ${{ env.REGISTRY }}/${{ github.repository }}/frontend
+          tags: |
+            type=ref,event=branch
+            type=ref,event=pr
+            type=semver,pattern={{version}}
+            type=semver,pattern={{major}}.{{minor}}
+            type=sha
+      -
+        name: Login to GHCR
+        uses: docker/login-action@v3
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+      -
+        name: Build and push
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          file: ./src/frontend/Dockerfile
+          target: frontend-production
+          build-args: |
+            DOCKER_USER=${{ env.DOCKER_USER }}:-1000
+            PUBLISH_AS_MIT=false
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}
+      -
+        name: Cleanup Docker after build
+        if: always()
+        run: |
+          docker system prune -af
+          docker volume prune -f
+
+  build-and-push-y-provider:
+    runs-on: ubuntu-latest
+    if: github.event.repository.fork == true
+    permissions:
+      contents: read
+      packages: write
+    steps:
+      -
+        name: Checkout repository
+        uses: actions/checkout@v4
+      -
+        name: Docker meta
+        id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: ${{ env.REGISTRY }}/${{ github.repository }}/y-provider
+          tags: |
+            type=ref,event=branch
+            type=ref,event=pr
+            type=semver,pattern={{version}}
+            type=semver,pattern={{major}}.{{minor}}
+            type=sha
+      -
+        name: Login to GHCR
+        uses: docker/login-action@v3
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+      -
+        name: Build and push
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          file: ./src/frontend/servers/y-provider/Dockerfile
+          target: y-provider
+          build-args: DOCKER_USER=${{ env.DOCKER_USER }}:-1000
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}
+      -
+        name: Cleanup Docker after build
+        if: always()
+        run: |
+          docker system prune -af
+          docker volume prune -f