fix(ci): hide models refresh from goreleaser dirty check

Use git update-index --assume-unchanged so the freshly downloaded
models.json does not make the working tree dirty for goreleaser.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: M09Ic

.github/workflows/release.yaml

@@ -19,8 +19,7 @@ jobs:
       - name: Refresh models catalog
         run: |
           curl -fsSL https://raw.githubusercontent.com/router-for-me/models/refs/heads/main/models.json -o internal/registry/models/models.json
-          git add -A
-          git diff --staged --quiet || git -c user.name="CI" -c user.email="ci@noreply" commit -m "chore: refresh models catalog"
+          git update-index --assume-unchanged internal/registry/models/models.json
       - run: git fetch --force --tags
       - uses: actions/setup-go@v4
         with: