test: migrate cross-arch tests to declarative test.toml; add WindowsViaWine

Collapses three outer-driver tests into declarative top-level fixtures:

  - CrossArchAarch64: outer + inner pair becomes main.cpp + test.toml. The
    'is this really an ARM aarch64 ELF?' artifact-introspection check is
    dropped — qemu-aarch64 refuses to run wrong-arch ELFs anyway, so a
    silent host-arch fallback would still fail the run.
  - Wasi: outer + inner pair becomes main.cpp + test.toml. The WASM
    magic-byte check is dropped on the same logic (wasmtime refuses
    non-WASM input).
  - Defines: simple defines-propagation smoke test becomes test.toml with
    [defines] CRAFTER_TEST_FOO = "42".

Adds WindowsViaWine to replace the (forthcoming-deletion) WindowsViaSsh:
declarative target=x86_64-w64-mingw32 + requires=[tool:wine,
tool:x86_64-w64-mingw32-g++]. Exercises the new Wine runner and the
ForTarget derivation end-to-end.

Diamond and CrossProjectModule had speculative --target= reading that
made them attempt cross-compilation under the multi-target sweep. They
have no sysroot/toolchain plumbing, so those cross-builds always fail.
Hardcoded them to HostTarget(); cross-arch tests live in their own
test.toml from now on.

Refs issue #8.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/Wasi/Wasi.cpp

@@ -1,44 +0,0 @@
-import std;
-import Crafter.Build;
-#include "../_shared/TestUtil.h"
-namespace fs = std::filesystem;
-using namespace TestUtil;
-using namespace Crafter;
-
-int main() {
-    try {
-        if (!fs::exists("/usr/share/wasi-sysroot/share/libc++/v1/std.cppm")) {
-            Skip("WASI sysroot/libc++ missing — install wasi-libc, wasi-libc++, wasi-libc++abi");
-        }
-
-        fs::path src = fs::current_path() / "tests" / "Wasi" / "inner";
-        Configuration cfg = LoadFixture("Wasi", src);
-        fs::path work = fs::current_path();
-
-        auto br = BuildOnce(cfg);
-        if (!br.result.empty()) {
-            std::println(std::cerr, "build failed:\n{}", br.result);
-            return 1;
-        }
-
-        fs::path artifact = cfg.BinDir() / "wasi-hello.wasm";
-        if (!fs::exists(artifact)) {
-            std::println(std::cerr, "expected artifact missing at {}", artifact.string());
-            return 1;
-        }
-
-        // Verify WASM magic bytes: \0asm
-        std::ifstream f(artifact, std::ios::binary);
-        char magic[4] = {};
-        f.read(magic, 4);
-        if (magic[0] != '\0' || magic[1] != 'a' || magic[2] != 's' || magic[3] != 'm') {
-            std::println(std::cerr, "artifact is not a valid WASM file (bad magic bytes)");
-            return 1;
-        }
-
-        return 0;
-    } catch (const std::exception& e) {
-        std::println(std::cerr, "test exception: {}", e.what());
-        return 1;
-    }
-}

tests/Wasi/inner/project.cpp

@@ -1,19 +0,0 @@
-import std;
-import Crafter.Build;
-namespace fs = std::filesystem;
-using namespace Crafter;
-
-extern "C" Configuration CrafterBuildProject(std::span<const std::string_view>) {
-    Configuration cfg;
-    cfg.path = "./";
-    cfg.name = "wasi-hello";
-    cfg.outputName = "wasi-hello";
-    cfg.target = "wasm32-wasip1";
-    cfg.type = ConfigurationType::Executable;
-
-    std::array<fs::path, 0> ifaces = {};
-    std::array<fs::path, 1> impls = { "main" };
-    cfg.GetInterfacesAndImplementations(ifaces, impls);
-
-    return cfg;
-}

tests/Wasi/project.cpp

@@ -1,20 +0,0 @@
-import std;
-import Crafter.Build;
-namespace fs = std::filesystem;
-using namespace Crafter;
-
-extern "C" Configuration CrafterBuildProject(std::span<const std::string_view>) {
-    Configuration cfg;
-    cfg.path = "tests/Wasi/";
-    cfg.name = "Wasi";
-    cfg.outputName = "Wasi";
-    cfg.target = "x86_64-pc-linux-gnu";
-    cfg.type = ConfigurationType::Executable;
-    cfg.dependencies = { ParentLib("crafter.build-lib") };
-    cfg.linkFlags.push_back("-Wl,--export-dynamic");
-    cfg.linkFlags.push_back("-ldl");
-    std::array<fs::path, 0> ifaces = {};
-    std::array<fs::path, 1> impls = { "Wasi" };
-    cfg.GetInterfacesAndImplementations(ifaces, impls);
-    return cfg;
-}

tests/Wasi/test.toml

@@ -0,0 +1,7 @@
+# WASI build via the WASI SDK's libc++ + the wasm32-wasip1 target. The
+# runner derivation routes the .wasm artifact through `wasmtime`.
+target = "wasm32-wasip1"
+requires = [
+    "tool:wasmtime",
+    "file:/usr/share/wasi-sysroot/share/libc++/v1/std.cppm",
+]