refactor: drop Windows host support

crafter-build is moving to a single Flatpak distribution, and there is
no Windows host in that picture: no build.cmd, no MSVC or mingw host
build, no DLL plus launcher. Delete every host-Windows path instead of
leaving it to rot unverified: the cmd.exe command runner and quoting,
the LOCALAPPDATA cache, the MSVC and mingw-host LoadProject variants
with their LIBCXX_DIR and CRAFTER_MINGW_DIR plumbing, the winsock port
probe, the LoadLibrary libclang loader, the console-width and isatty
shims, and the preprocessor guards around the Linux bodies.

The x86_64-w64-mingw32 cross-compile target stays. It is target logic
(output names, -femulated-tls, the libstdc++ link extras, copying a
dependency DLL next to a mingw exe, wine as the runner) and did not
depend on any of the removed code. The msvc target goes with the host
that was the only thing able to use it.

Three target-path warts fixed on the way: ExpectedOutput named a mingw
static library <name>.lib while the archive step wrote lib<name>.a, so
those libraries relinked on every run; the import lib is no longer
copied next to a mingw exe, since the dependency's own bin dir is
already on the link line; and llvm-ar now writes every archive, not
only the LTO ones, so Debug and Release archives are made the same way.

CRAFTER_API and Crafter.Build-Api.h existed only for the DLL boundary.
Nothing downstream used them, so they are removed rather than kept as
an empty macro nobody can verify.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

interfaces/Crafter.Build-Progress.cppm

@@ -1,22 +1,20 @@
 // SPDX-License-Identifier: LGPL-3.0-only
 // SPDX-FileCopyrightText: Copyright (C) 2026 Catcrafts®
 
-module;
-#include "Crafter.Build-Api.h"
 export module Crafter.Build:Progress;
 import std;
 
 export namespace Crafter::Progress {
     enum class Verbosity { Quiet, Default, Verbose };
 
-    CRAFTER_API void SetVerbosity(Verbosity v);
-    CRAFTER_API Verbosity GetVerbosity();
+    void SetVerbosity(Verbosity v);
+    Verbosity GetVerbosity();
 
     // RAII work-unit marker. Construction inflates the running total; destruction
     // increments completed and (on Default + TTY) redraws the status line. Move
     // semantics are disabled — keep these as plain stack locals inside the worker
     // lambda so the destructor fires when that thread's work ends.
-    class CRAFTER_API Task {
+    class Task {
     public:
         explicit Task(std::string label);
         ~Task();
@@ -29,18 +27,18 @@ export namespace Crafter::Progress {
     };
 
     // Verbose-mode command echo. No-op outside Verbose.
-    CRAFTER_API void EchoCommand(std::string_view command);
+    void EchoCommand(std::string_view command);
 
     // Non-fatal output from a build step that succeeded — compiler and linker
     // warnings. Erases the status line first so the text doesn't land on top of
     // it, then writes to stderr. No-op on Quiet.
-    CRAFTER_API void Diagnostic(std::string_view text);
+    void Diagnostic(std::string_view text);
 
     // Erase the in-place status line so subsequent stderr writes (errors,
     // banners) don't collide with it. No-op when not in TTY-redraw mode.
-    CRAFTER_API void Clear();
+    void Clear();
 
     // Print "Built N targets in Xms" (or equivalent) and clear in-place state.
     // Safe to call multiple times; subsequent calls are no-ops.
-    CRAFTER_API void Finalize();
+    void Finalize();
 }