fix(window): set the title on Win32 through a Unicode window class, and send only the view's bytes on Wayland

Win32
- SetTitle had a body only for Wayland, so the title passed to Window's
  constructor and every later SetTitle left a Win32 window untitled. It
  converts the title from UTF-8 and hands it to SetWindowTextW.
- The window class is registered with RegisterClassW, the window made
  with CreateWindowExW, and WndProc hands what it does not handle to
  DefWindowProcW. An ANSI class has the text of every message converted
  to the process code page on its way to WndProc, so SetWindowTextW
  alone would not do: under Wine, in CP1252, 日本 in a title came back
  as ??. WM_CHAR, whose handler takes wParam for a UTF-16 code unit, got
  € as its CP1252 byte 0x80 and passed it on as U+0080, and 日 and both
  halves of a surrogate pair as ?.
- Both message pumps use PeekMessageW and DispatchMessageW. PeekMessageA
  converts WM_CHAR to the code page whatever the window's class: on the
  Unicode class, an ANSI pump still turned 日 and the surrogates into ?.

Wayland
- SetTitle handed title.data() to xdg_toplevel_set_title, which reads up
  to a NUL: a view into a longer string sent the whole string, and an
  empty view's null data() made libwayland fail the display with EINVAL.
  It copies the view into a std::string, as SetAppId does.

Tests
- TextWin32: the constructor's title, SetTitle with characters outside
  the code page, with a view into a longer string and with an empty
  title, read back with GetWindowTextW; and é, €, 日 and a surrogate
  pair posted as WM_CHAR and delivered by StartSync's own loop, which
  returns on the WM_CLOSE posted after them, so a StartSync pumping with
  the A functions fails it. The window is disabled, so a real keystroke
  can't reach the check. Without the fix every check but the empty title
  fails. Like PointerWin32, built on Linux it runs under Wine.
- TitleWayland: SetTitle's set_title requests, read off a wl_display
  connected to a socketpair, for a view into a longer string and for an
  empty view. Both checks fail without the fix. No compositor.
- PointerWin32 pumps with the W functions, as StartSync now does.

Docs
- AGENTS.md names TextWin32 beside PointerWin32 as the Win32 tests, says
  what their Wine runs needed (the vulkan-1 import library, -luuid, which
  the link flags lack, #184, and a __libc_single_threaded definition),
  and lists TitleWayland among the tests that need no GPU.

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

project.cpp

@@ -337,6 +337,16 @@ extern "C" Configuration CrafterBuildProject(std::span<const std::string_view> a
             win32PointerTest.requires_ = { "tool:wine" };
             #endif
             cfg.tests.push_back(std::move(win32PointerTest));
+
+            // The Win32 backend's text, UTF-8 to the library and UTF-16 to
+            // Windows: the title from the constructor and SetTitle, read back
+            // from the HWND, and the characters WM_CHAR brings. Needs what
+            // PointerWin32 needs.
+            Test win32TextTest = LibraryTest("TextWin32");
+            #ifndef _WIN32
+            win32TextTest.requires_ = { "tool:wine" };
+            #endif
+            cfg.tests.push_back(std::move(win32TextTest));
         }
 
         // Regression test for issue #32: the Wayland scroll-wheel chain
@@ -351,6 +361,11 @@ extern "C" Configuration CrafterBuildProject(std::span<const std::string_view> a
             // Drives the wl_pointer callbacks directly, as MouseScroll does.
             cfg.tests.push_back(LibraryTest("PointerEnterLeave"));
 
+            // SetTitle's xdg_toplevel.set_title, read off a wl_display on a
+            // socketpair: the view's bytes only, and an empty view as an
+            // empty title, not a null string. No compositor.
+            cfg.tests.push_back(LibraryTest("TitleWayland"));
+
             // Issue #40: multi-frame-in-flight frame pacing (per-frame fences
             // and acquire semaphores, per-image render-finished semaphores, no
             // steady-state wait-idle). Drives the