The Amiibo tab's folder field took no typing: the menu never passes typed characters to Dear ImGui, so "Open" only
re-read "./amiibo". A missing folder said so at the bottom of the right pane, below its scroll.
"Open" now shows the shell's folder dialog on Windows (IFileOpenDialog on a thread of its own, owned by the game
window) and SDL_ShowOpenFolderDialog on the SDL window thread elsewhere; the tab shows the folder as text and names a
missing one inside the empty list.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Shared runtime code now goes through runtime/platform/platform.h, implemented by platform/win32.c and a new
platform/linux.c: futex locks, a userfaultfd and PAGEMAP_SCAN write watch, signal-based async preemption, our own
fiber switch, and a SIGSEGV handler for the thaw and crash hooks. The window, input, menu and software keyboard get
SDL3 back ends beside the Win32 ones, with the swapchain (gfx_present.c) and input merging (input.c) shared. SHA-256
replaces BCrypt, ELF builds get their own override sections, and the build tools gain Linux branches.
On Linux the selftest and the gfx-abi, astc, nvn and window probes pass. probe-vkmem still fails: imported guest
memory cannot be write-watched on Linux, which the shadow buffers in vk_memory.c will address.
