chore: gitignore generated protobuf files (catalogpb/*.pb.go)

Generated files should be rebuilt with `make proto`, not checked in.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Signed-off-by: shaoting-huang <shaoting.huang@zilliz.com>

Author: shaoting-huang

.gitignore

@@ -5,6 +5,9 @@ bin/
 *.so
 *.dylib
 
+# Generated protobuf
+catalogpb/*.pb.go
+
 # Build artifacts
 *.o
 *.a