ci: delete existing release before recreating on retrigger

Prevents curl exit 22 (HTTP 409) when a tag's release already exists.

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

.gitea/workflows/release.yml

@@ -41,11 +41,20 @@ jobs:
         id: create_release
         run: |
           TAG="${{ github.ref_name }}"
+          API="${{ github.server_url }}/api/v1/repos/${{ github.repository }}"
+          AUTH="Authorization: token ${{ secrets.GITEA_TOKEN }}"
+
+          # Delete existing release for this tag if present
+          EXISTING=$(curl -sf -H "$AUTH" "$API/releases/tags/$TAG" | python3 -c "import sys,json; print(json.load(sys.stdin).get('id',''))" 2>/dev/null || true)
+          if [ -n "$EXISTING" ]; then
+            echo "Deleting existing release $EXISTING"
+            curl -sf -X DELETE -H "$AUTH" "$API/releases/$EXISTING"
+          fi
 
           RELEASE=$(curl -sf -X POST \
-            -H "Authorization: token ${{ secrets.GITEA_TOKEN }}" \
+            -H "$AUTH" \
             -H "Content-Type: application/json" \
-            "${{ github.server_url }}/api/v1/repos/${{ github.repository }}/releases" \
+            "$API/releases" \
             -d "{
               \"tag_name\": \"$TAG\",
               \"name\": \"$TAG\",