Check for existing release before building

Fail early with clear error if the specified version already exists.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.forgejo/workflows/build-blumeops.yaml

@@ -57,6 +57,13 @@ jobs:
             fi
           fi
 
+          # Check if this version already exists
+          if curl -sf "https://forge.ops.eblu.me/api/v1/repos/eblume/blumeops/releases/tags/$VERSION" > /dev/null 2>&1; then
+            echo "Error: Release $VERSION already exists"
+            echo "See: https://forge.ops.eblu.me/eblume/blumeops/releases/tag/$VERSION"
+            exit 1
+          fi
+
           echo "version=$VERSION" >> "$GITHUB_OUTPUT"
           echo "Building BlumeOps release: $VERSION"