Resize previously always destroyed + reallocated. It now reuses the
existing allocation in place when the new request still fits the created
capacity and the immutable-at-create properties match: usage flags are
fixed at create, and the chosen memory type must still satisfy the
required property flags. preferredPropertyFlags is a best-effort perf
hint and is intentionally not part of the guard. On reuse the buffer
handle, device address and mapped pointer are preserved; only `size`
shrinks to the new logical extent.
Tracks capacity and the created usage flags on VulkanBufferBase, set at
Create and carried through the move constructor.
Adds VulkanBufferResizeReuse, a device-free regression test that drives
the reuse guard directly and asserts the in-place path issues no Vulkan
call.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
