Add owned Vulkan buffer API

[antono3]

Summary

• add physical-device memory property snapshots and compatible memory-type selection
• add an owned buffer/device-memory composite with explicit property requirements and safe cleanup order
• document buffer lifetime rules and cover memory selection edge cases

Validation

• v fmt -verify ergonomic/ergonomic.v ergonomic/ergonomic_test.v
• v -check-syntax ergonomic/ergonomic.v
• v -check-syntax ergonomic/ergonomic_test.v
• full compilation delegated to GitHub Actions per repository guidance