fix(ci): 使用预处理的小写 owner 替代 lower 函数

GoReleaser 不支持 lower 模板函数，改为：
- 在 GitHub Actions 中预处理小写 owner
- 传递 GITHUB_REPO_OWNER_LOWER 环境变量给 GoReleaser

.github/workflows/release.yml

@@ -129,6 +129,10 @@ jobs:
           echo "$TAG_MESSAGE" >> $GITHUB_OUTPUT
           echo "EOF" >> $GITHUB_OUTPUT
 
+      - name: Set lowercase owner for GHCR
+        id: lowercase
+        run: echo "owner=$(echo '${{ github.repository_owner }}' | tr '[:upper:]' '[:lower:]')" >> $GITHUB_OUTPUT
+
       - name: Run GoReleaser
         uses: goreleaser/goreleaser-action@v6
         with:
@@ -138,6 +142,7 @@ jobs:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
           TAG_MESSAGE: ${{ steps.tag_message.outputs.message }}
           GITHUB_REPO_OWNER: ${{ github.repository_owner }}
+          GITHUB_REPO_OWNER_LOWER: ${{ steps.lowercase.outputs.owner }}
           GITHUB_REPO_NAME: ${{ github.event.repository.name }}
           DOCKERHUB_USERNAME: ${{ secrets.DOCKERHUB_USERNAME }}