fix(win32): link the Vulkan loader without a Vulkan SDK, link libuuid, and check that a Win32 executable links

Build
- The MinGW toolchains ship no import library for vulkan-1.dll, so
  without a Vulkan SDK's every Win32 executable stopped at "unable to
  find library -lvulkan-1". project.cpp now makes one with the
  llvm-dlltool beside the toolchain's llvm-ar, from Vulkan-Loader's
  loader/vulkan-1.def. That is the loader's own list of what
  vulkan-1.dll exports, fetched with GitFetch, unpinned like
  Vulkan-Headers, so the API the library compiles against and the
  exports it links against move together. The import library the Wine
  runs used, made from the calls the library happened to make, went
  stale with the next new call (234fcce added
  vkEnumerateInstanceExtensionProperties). The loader's list does not,
  and a call it does not export fails at link time instead of when the
  exe starts.
- It is made into build/vulkan-1-<target>/ when a stamp beside it,
  holding the command and the .def it was made from, no longer matches;
  a fetch or a copy says nothing through the .def's mtime. It goes into
  the link by its absolute path rather than through -L, so it shadows
  no consumer's Vulkan SDK library. A failed fetch or llvm-dlltool run
  is a Progress::Diagnostic warning, and the link falls back to the
  library a previous load made, or to -lvulkan-1.
- -luuid joins the Win32 link flags: the gamepad code compares against
  IID_IUnknown and IID_IAgileObject, and StartSync's Gamepad::Tick pulls
  it into every executable (#184).
- project.cpp uses ShellQuote, exported from crafter-build 3.0.0, which
  is now the minimum.

Tests
- Win32Link: an executable that uses the library as an application does
  (Device::Initialize, a Window, StartSync) links. Without Wine it runs
  as --runner=cmd:true, which builds it and runs nothing; under Wine it
  also opens a window and closes it. It fails to link without -luuid
  (IID_IUnknown, IID_IAgileObject) and without the import library
  ("unable to find library -lvulkan-1"). Under the Flatpak it needs
  tests/Win32Link/libc-single-threaded.c, which stands in for
  Catcrafts/Crafter.Build#43 and goes with it.
- With the native crafter-build on the host, which has Wine and finds
  the host's mingw-w64 itself, PointerWin32, TextWin32 and Win32Link now
  build and pass under Wine with nothing added.

Docs
- AGENTS.md: the minimum crafter-build, the Vulkan-Loader fetch and what
  project.cpp runs, the Win32Link check in the commands and the
  done-list, and a one-line Wine recipe in place of the hand-built
  import library, shim and project.cpp edit. AGENTS.consumer.md: the
  minimum, how the import library is made, and the
  __libc_single_threaded workaround under the Flatpak. README: the
  minimum, the Win32 build command, and that it needs no Vulkan SDK.

Closes #184.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/Win32Link/libc-single-threaded.c

@@ -0,0 +1,11 @@
+//SPDX-License-Identifier: LGPL-3.0-only
+//SPDX-FileCopyrightText: Copyright (C) 2026 Catcrafts®
+
+// Stands in for Crafter.Build #43, and goes when that is fixed, with its line
+// in project.cpp. In the Flatpak the MinGW sysroot is the host's /usr, which
+// puts glibc's headers on the include path, so the libstdc++ shared_ptr that
+// nlohmann/json inlines into Crafter.Asset's GLB loader reads glibc's
+// __libc_single_threaded, which no Windows library defines. Zero means "not
+// single-threaded", so the reference counts stay atomic, as they would be
+// without the leak.
+char __libc_single_threaded = 0;