ci: read the zip list with cut, not a bash-only IFS

The upload loop used IFS=$'\t', but the job steps run under /bin/sh,
which is dash in the builder image. dash does not expand $'\t', so IFS
became the characters $, \ and t and every path was split on "t":
"artifacts/srfplay_1.2.0.9.zip" reached curl as "s/srfplay_...", which
failed with exit 26 after the release had already been created. This
broke both the v1.2.0 release and the nightly.

cut -f3 is plain POSIX. Checked by running the upload and manifest
steps under the builder image's dash with curl stubbed.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

.gitea/workflows/release.yaml

@@ -91,14 +91,14 @@ jobs:
           fi
 
           # Upload one plugin zip per Jellyfin generation
-          while IFS=$'\t' read -r _ _ ZIP _; do
+          cut -f3 artifacts/builds.tsv | while read -r ZIP; do
             echo "Uploading ${ZIP}..."
             curl -f -X POST \
               -H "Authorization: token ${GITEA_TOKEN}" \
               -H "Content-Type: application/zip" \
               --data-binary "@${ZIP}" \
               "${GITEA_URL}/api/v1/repos/${REPO_OWNER}/${REPO_NAME}/releases/${RELEASE_ID}/assets?name=$(basename "${ZIP}")"
-          done < artifacts/builds.tsv
+          done
 
           # Upload build.yaml
           echo "Uploading build.yaml..."