PHLEGM v8 Checkpoint 11: Windows owner bridge + Vulkan recovery
Parent: PHLEGM-v8-Developer-Distribution-Linux-D3D11-Vulkan-Forward-10-2026-1007-1601-5296.zip

Implemented:
- Windows SDL machine-display handles are translated through SDL_GetWindowWMInfo before use as MessageBox owners. Registered SDL_Window pointers are no longer passed directly to Win32 MessageBoxA as though they were HWND values.
- Windows dynamic SDL dispatch now loads SDL_GetVersion and SDL_GetWindowWMInfo. The SysWM bridge uses SDL2's fixed C ABI offsets via an opaque 72-byte buffer, avoiding FreeBASIC structure-packing dependencies.
- Vulkan presentation now retries one time after VK_ERROR_OUT_OF_DATE_KHR from acquire or present by releasing and recreating the swapchain.
- VK_SUBOPTIMAL_KHR is accepted for the current frame, then the swapchain is retired so the next frame recreates it.
- Partial Vulkan swapchain/staging allocation failures now funnel through one cleanup path, preventing stale partial swapchain resources from surviving a failed resize/recreate.
- Checkpoint 10 Linux D3D11 compatibility routing through gfx_vulkan.lib remains structural and unchanged.
- Existing tree.lib/archive.lib, tree/icons mode, Packard Bell CHR GUI font, PPU/APU Skip controls, FPS/frame-skip overlay, and Windows OpenGL/D3D11 policy are retained.

Validation in this environment:
- PASS: independent GCC ABI probes for x86 and x86_64 confirm SDL_SysWMinfo size 72 bytes, subsystem offset 4, platform union offset 8, and Windows HWND at offset 8.
- PASS: source assertions confirm Windows HostConfirm resolves registered SDL owners through HostSDLNativeWindowHandle before MessageBoxA.
- PASS: source assertions confirm Vulkan out-of-date acquire/present retry, suboptimal retirement, and transactional resize cleanup are present.
- PASS: changed normal text sources use CRLF only.
- PASS: inherited Linux D3D11 compatibility selector still resolves to gfx_vulkan.lib; Windows Vulkan remains excluded by policy.

Limitations:
- fbc is not installed/exposed in this container, so Checkpoint 11 does not claim a fresh native FreeBASIC compile/link.
- No graphical Windows desktop, Linux display server, or Vulkan ICD is available here; actual dialog parenting and Vulkan WSI behavior still require runtime verification on those hosts.
- Historical Checkpoint 08/07 compile/runtime diagnostics remain prior evidence only, not a fresh Checkpoint 11 matrix compile.
