fix(ci): use git switch to avoid deploy dir/branch ambiguity

'git checkout deploy' is ambiguous because the repo contains both a
deploy/ directory and a deploy remote tracking branch. Switch to
'git switch' which is branch-only and unambiguous.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

.gitea/workflows/docker-build.yml

@@ -66,7 +66,12 @@ jobs:
           git config user.email "ci@gitea.local"
           git config user.name "Gitea CI"
           # Switch to the deploy branch, creating it from the current HEAD if absent.
-          git fetch origin deploy 2>/dev/null && git checkout deploy || git checkout -b deploy
+          # Use 'git switch' (branch-only) to avoid ambiguity with the deploy/ directory.
+          if git fetch origin deploy 2>/dev/null; then
+            git switch deploy
+          else
+            git switch -c deploy
+          fi
           # Update the pinned image tag.
           cd deploy
           kustomize edit set image solitaire-server=${{ env.IMAGE }}:${{ steps.meta.outputs.sha }}