feat: add Gitea actions to sync releases to GitHub

Add two new workflows:
- sync-release.yml: automatically mirrors releases (with assets) to GitHub when published on Gitea
- backfill-releases.yml: manual workflow to bulk-sync all existing Gitea releases to GitHub

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

.gitea/workflows/sync-release.yml

@@ -0,0 +1,60 @@
+name: Sync Release to GitHub
+
+on:
+  release:
+    types: [published]
+
+jobs:
+  sync-release:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Mirror release to GitHub
+        env:
+          GH_PAT: ${{ secrets.GH_PAT }}
+          GITHUB_REPO: shadowdao/triple-c
+          RELEASE_TAG: ${{ gitea.event.release.tag_name }}
+          RELEASE_NAME: ${{ gitea.event.release.name }}
+          RELEASE_BODY: ${{ gitea.event.release.body }}
+          IS_PRERELEASE: ${{ gitea.event.release.prerelease }}
+          IS_DRAFT: ${{ gitea.event.release.draft }}
+        run: |
+          set -e
+
+          echo "==> Creating release $RELEASE_TAG on GitHub..."
+
+          RESPONSE=$(curl -sf -X POST \
+            -H "Authorization: Bearer $GH_PAT" \
+            -H "Accept: application/vnd.github+json" \
+            -H "Content-Type: application/json" \
+            https://api.github.com/repos/$GITHUB_REPO/releases \
+            -d "{
+              \"tag_name\": \"$RELEASE_TAG\",
+              \"name\": \"$RELEASE_NAME\",
+              \"body\": $(echo "$RELEASE_BODY" | jq -Rs .),
+              \"draft\": $IS_DRAFT,
+              \"prerelease\": $IS_PRERELEASE
+            }")
+
+          UPLOAD_URL=$(echo "$RESPONSE" | jq -r '.upload_url' | sed 's/{?name,label}//')
+          echo "Release created. Upload URL: $UPLOAD_URL"
+
+          echo '${{ toJSON(gitea.event.release.assets) }}' | jq -c '.[]' | while read asset; do
+            ASSET_NAME=$(echo "$asset" | jq -r '.name')
+            ASSET_URL=$(echo "$asset" | jq -r '.browser_download_url')
+
+            echo "==> Downloading asset: $ASSET_NAME"
+            curl -sfL -o "/tmp/$ASSET_NAME" "$ASSET_URL"
+
+            echo "==> Uploading $ASSET_NAME to GitHub..."
+            ENCODED_NAME=$(python3 -c "import urllib.parse, sys; print(urllib.parse.quote(sys.argv[1]))" "$ASSET_NAME")
+            curl -sf -X POST \
+              -H "Authorization: Bearer $GH_PAT" \
+              -H "Accept: application/vnd.github+json" \
+              -H "Content-Type: application/octet-stream" \
+              --data-binary "@/tmp/$ASSET_NAME" \
+              "$UPLOAD_URL?name=$ENCODED_NAME"
+
+            echo "  Uploaded: $ASSET_NAME"
+          done
+
+          echo "==> Release sync complete."