[woterr]

This Pull Request fixes/closes #5655

It changes the following:

• Accounts for each level of the FlattenIntoArray native self-recursion via context.vm.host_call_depth and enforces the configured recursion_limit through context.check_runtime_limits() at the recursive call site — the same mechanism the VM already uses for nested host calls and deep JS recursion. Hitting the limit raises the existing RuntimeLimitError::Recursion instead of aborting the process.
• Adds a regression test covering a self-referential array with flat(Infinity), finite-depth nesting beyond the recursion limit, and flat(0) on a self-referential array (still flattens one level, no over-blocking).