ci: add HuggingFace mirror on tag release

Pushes to huggingface.co/lthn/LEM-Gemma3-1B on v* tags.
Requires HF_TOKEN secret in org/repo settings.

Co-Authored-By: Virgil <virgil@lethean.io>

.forgejo/workflows/mirror-hf.yml

@@ -0,0 +1,25 @@
+name: Mirror to HuggingFace
+
+on:
+  push:
+    tags: ['v*']
+
+jobs:
+  mirror:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout with LFS
+        uses: actions/checkout@v4
+        with:
+          lfs: true
+          fetch-depth: 0
+
+      - name: Push to HuggingFace
+        env:
+          HF_TOKEN: ${{ secrets.HF_TOKEN }}
+          HF_REPO: ${{ vars.HF_REPO || 'lthn/LEM-Gemma3-1B' }}
+        run: |
+          git remote add hf "https://Virgil:${HF_TOKEN}@huggingface.co/${HF_REPO}"
+          git push hf main --force
+          git push hf --tags
+          echo "Mirrored ${GITHUB_REF_NAME} → huggingface.co/${HF_REPO}"