Add CI workflow + remove upstream GitHub workflows

Builds deb Dockerfile, pushes to registry.johnogle.info/protonmail-bridge.
No auto-deploy — temporary fork until upstream merges libfido2 patch.

Requires secrets: REGISTRY_USERNAME, REGISTRY_PASSWORD

.gitea/workflows/build-and-push.yml

@@ -0,0 +1,43 @@
+name: Build and Push Docker Image
+
+on:
+  push:
+    branches: [master]
+  workflow_dispatch:
+
+permissions:
+  contents: read
+  actions: write
+
+jobs:
+  build-and-push:
+    name: Build & Push Docker Image
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Generate image metadata
+        id: meta
+        run: |
+          VERSION=$(cat deb/PACKAGE | grep -oP '\d+\.\d+\.\d+' | head -1 || echo "unknown")
+          SHORT_SHA=$(echo "${{ github.sha }}" | cut -c1-7)
+          echo "tag=${VERSION}-${SHORT_SHA}" >> $GITHUB_OUTPUT
+          echo "Image will be tagged: ${VERSION}-${SHORT_SHA}"
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Login to registry
+        run: |
+          echo "${{ secrets.REGISTRY_PASSWORD }}" | docker login registry.johnogle.info -u ${{ secrets.REGISTRY_USERNAME }} --password-stdin
+
+      - name: Build and push (deb)
+        uses: docker/build-push-action@v5
+        with:
+          context: ./deb
+          push: true
+          tags: |
+            registry.johnogle.info/protonmail-bridge:${{ steps.meta.outputs.tag }}
+            registry.johnogle.info/protonmail-bridge:latest
+          platforms: linux/amd64