feat: update Docker image build workflow to use dynamic registry URL and improve tag handling

.gitea/workflows/build-image.yaml

@@ -0,0 +1,59 @@
+name: Build Docker Image
+
+on:
+  push:
+    branches:
+      - main
+    tags:
+      - '*'
+
+env:
+  GITEA_REGISTRY: ${{ gitea.server_url }}
+  GITEA_USERNAME: ${{ gitea.actor }}
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+      
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+      
+      - name: Determine image tag
+        id: tag
+        run: |
+          if [[ "${{ github.ref }}" == refs/tags/* ]]; then
+            TAG=${GITHUB_REF#refs/tags/}
+          elif [[ "${{ github.ref }}" == "refs/heads/main" ]]; then
+            TAG=main
+          else
+            echo "Not on main branch or a tag, skipping build"
+            exit 1
+          fi
+          echo "tag=$TAG" >> $GITHUB_OUTPUT
+          
+          # Remove protocol from registry URL
+          REGISTRY="${{ env.GITEA_REGISTRY }}"
+          REGISTRY="${REGISTRY#https://}"
+          REGISTRY="${REGISTRY#http://}"
+          echo "registry=$REGISTRY" >> $GITHUB_OUTPUT
+      
+      - name: Login to Gitea Container Registry
+        uses: docker/login-action@v3
+        with:
+          registry: ${{ steps.tag.outputs.registry }}
+          username: ${{ vars.REGISTRY_USERNAME }}
+          password: ${{ secrets.REGISTRY_TOKEN }}
+      
+      - name: Build and push Docker image
+        uses: docker/build-push-action@v5
+        with:
+          context: .
+          file: ./Dockerfile
+          push: true
+          tags: |
+            ${{ steps.tag.outputs.registry }}/${{ gitea.repository }}:${{ steps.tag.outputs.tag }}
+            ${{ steps.tag.outputs.registry }}/${{ gitea.repository }}:latest