Keep the latest upload-staging and compact-binding fixes from main. Add a real-Metal readback lifetime regression and reference documentation for all three general fixes.
Validation: nine Metal test runs pass, including direct and deferred upload-budget tests; Wonder host build, 133-file iOS compile check, and documentation checks pass.
Co-authored-by: Aleksandr Svidchenkov <a.svidchenkov@gmail.com>
Split GPU upload batches at 128 MiB and retire overflow and CPU staging when the upload completes, rather than retaining it until the main rendering fence. Scope weak-reference diagnostics to avoid temporary staging retention.
Add a real-Metal regression covering memory bounds, upload pixels and an open render pass in direct and deferred encoding modes. Both modes pass 261 checks; documentation checks and the TotK host build pass.
Refs #147. Reporter-device validation and the full-device reboot investigation remain open.
