Fix publish workflow: use git archive instead of go install

golang.org/x/mod/zip is a library, not a CLI tool. Use git archive
with --prefix to create the module zip in the format Gitea expects.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.gitea/workflows/publish.yml

@@ -24,9 +24,9 @@ jobs:
         run: |
           VERSION=${GITHUB_REF#refs/tags/}
           MODULE=$(go list -m)
-          go mod download
+
-          GOFLAGS=-mod=mod go install golang.org/x/mod/zip@latest
+          # Create module zip with required prefix: module@version/
-          zip -r module.zip . -x '.git/*' '.gitea/*'
+          git archive --format=zip --prefix="${MODULE}@${VERSION}/" HEAD -o module.zip
 
           # Gitea Go Package Registry API
           curl -s -f \