Commit to the godot-cpp fork

The godot-cpp submodule tracks utopia-rise/godot-cpp, branch godot-jvm: not upstream godotengine/godot-cpp, and not the fork's master. The branch adapts godot-cpp's generated bindings to Godot-JVM's object-tracking model; it is not a collection of upstream fixes.

1. Commit in the submodule, on godot-jvm, and in the same commit append an entry to the fork's godot-cpp-divergence.md: what the change does and why Godot-JVM needs it. Add the commit hash to the entry with an amend once it is known, or in the next fork commit.
2. Push to utopia-rise/godot-cpp, branch godot-jvm. This is an outward action: confirm with the maintainer first.
3. Update the pointer in this repository: git -C godot-cpp checkout <new commit>, then git add godot-cpp, committed with the change that needs it.
4. Re-read the "godot-cpp fork" section of the root CLAUDE.md and docs/src/doc/contribute/godot-cpp-fork.md; update them if the branch moved onto a newer upstream tag.

Then rebuild the native library (check-cpp skill): godot-cpp changes affect every target.