feat(selfhost): ship public GHCR deployment flow

Publish stable GHCR self-host images, switch self-host deploys to official image pulls with a source-build fallback, and move self-host signup / Google OAuth config onto runtime /api/config.

.github/workflows/release.yml

@@ -10,10 +10,14 @@ on:
 
 permissions:
   contents: write
+  packages: write
 
 jobs:
-  release:
+  verify:
     runs-on: ubuntu-latest
+    outputs:
+      tag_name: ${{ steps.release_meta.outputs.tag_name }}
+      is_stable: ${{ steps.release_meta.outputs.is_stable }}
     steps:
       - name: Checkout
         uses: actions/checkout@v4
@@ -21,6 +25,8 @@ jobs:
           fetch-depth: 0
 
       - name: Validate tag name
+        id: release_meta
+        shell: bash
         run: |
           tag="${GITHUB_REF_NAME}"
           echo "Triggered by tag: $tag"
@@ -32,6 +38,12 @@ jobs:
             echo "::error::Refusing to release from dirty tag '$tag'."
             exit 1
           fi
+          echo "tag_name=$tag" >> "$GITHUB_OUTPUT"
+          if [[ "$tag" == *-* ]]; then
+            echo "is_stable=false" >> "$GITHUB_OUTPUT"
+          else
+            echo "is_stable=true" >> "$GITHUB_OUTPUT"
+          fi
 
       - name: Setup Go
         uses: actions/setup-go@v5
@@ -42,6 +54,21 @@ jobs:
       - name: Run tests
         run: cd server && go test ./...
 
+  release:
+    needs: verify
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Setup Go
+        uses: actions/setup-go@v5
+        with:
+          go-version-file: server/go.mod
+          cache-dependency-path: server/go.sum
+
       - name: Run GoReleaser
         uses: goreleaser/goreleaser-action@v6
         with:
@@ -51,6 +78,91 @@ jobs:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
           HOMEBREW_TAP_GITHUB_TOKEN: ${{ secrets.HOMEBREW_TAP_GITHUB_TOKEN }}
 
+  docker-images:
+    needs: verify
+    runs-on: ubuntu-latest
+    concurrency:
+      group: release-docker-images-${{ github.ref }}
+      cancel-in-progress: true
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup QEMU
+        uses: docker/setup-qemu-action@v3
+
+      - name: Setup Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Login to GHCR
+        uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Compute backend image tags
+        id: meta_backend
+        uses: docker/metadata-action@v5
+        with:
+          images: ghcr.io/${{ github.repository_owner }}/multica-backend
+          flavor: |
+            latest=false
+          tags: |
+            type=raw,value=latest,enable=${{ needs.verify.outputs.is_stable == 'true' }}
+            type=raw,value=${{ needs.verify.outputs.tag_name }}
+            type=sha,prefix=sha-
+          labels: |
+            org.opencontainers.image.title=Multica Backend
+            org.opencontainers.image.description=Multica self-hosted backend
+
+      - name: Build and push backend image
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          file: Dockerfile
+          pull: true
+          push: true
+          platforms: linux/amd64,linux/arm64
+          labels: ${{ steps.meta_backend.outputs.labels }}
+          tags: ${{ steps.meta_backend.outputs.tags }}
+          cache-from: type=gha,scope=release-backend
+          cache-to: type=gha,mode=max,scope=release-backend
+          build-args: |
+            VERSION=${{ needs.verify.outputs.tag_name }}
+            COMMIT=${{ github.sha }}
+
+      - name: Compute web image tags
+        id: meta_web
+        uses: docker/metadata-action@v5
+        with:
+          images: ghcr.io/${{ github.repository_owner }}/multica-web
+          flavor: |
+            latest=false
+          tags: |
+            type=raw,value=latest,enable=${{ needs.verify.outputs.is_stable == 'true' }}
+            type=raw,value=${{ needs.verify.outputs.tag_name }}
+            type=sha,prefix=sha-
+          labels: |
+            org.opencontainers.image.title=Multica Web
+            org.opencontainers.image.description=Multica self-hosted web frontend
+
+      - name: Build and push web image
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          file: Dockerfile.web
+          pull: true
+          push: true
+          platforms: linux/amd64,linux/arm64
+          labels: ${{ steps.meta_web.outputs.labels }}
+          tags: ${{ steps.meta_web.outputs.tags }}
+          cache-from: type=gha,scope=release-web
+          cache-to: type=gha,mode=max,scope=release-web
+          build-args: |
+            REMOTE_API_URL=http://backend:8080
+            NEXT_PUBLIC_APP_VERSION=${{ needs.verify.outputs.tag_name }}
+
   # Build the Desktop installers for Linux and Windows and upload them to
   # the GitHub Release that the `release` job above just published. macOS
   # Desktop continues to ship via the manual `release-desktop` skill so it