test(windows): build and run the test suite for Windows from WSL

scripts/test-windows.sh cross-compiles ObsidianDragonTests.exe (and the
fake_dragonxd stub) with mingw into build/windows-tests, reusing the
toolchain and dependency sources from build/windows, and runs it from
WSL through Windows interop (or wine). All tests pass on Windows.

CMake:
- Windows forced BUILD_TESTING OFF in the cache to keep curl's tests
  out, which also removed ObsidianDragonTests from every Windows build.
  Hide it from curl with a scoped variable instead, and restore our
  cache value afterwards (curl's cmake_dependent_option FORCE-writes
  it). Windows still defaults to OFF, so release builds are unchanged.
- ObsidianDragonTests now depends on copy_langs: i18n.cpp includes the
  generated embedded/lang_*.h, so a tree that builds only the tests
  failed (latent on Linux too).
- Link the Windows system libraries the tests need.

Tests:
- testTmpPath/fixtureDir/removeTree helpers: no hard-coded /tmp, a
  runtime fixture-dir override (the compiled-in path is a Linux one),
  and best-effort cleanup that can't abort the suite.
- Close the explorer cache before deleting its directory (Windows
  can't delete an open file).
- Compile out the address-book and wallet-index round-trips on Windows:
  getConfigDir() uses SHGetFolderPath there, which no environment
  variable redirects, so they would overwrite the real
  %APPDATA%\ObsidianDragon files.

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

scripts/test-windows.sh

@@ -0,0 +1,76 @@
+#!/usr/bin/env bash
+# Cross-compile the test suite (ObsidianDragonTests.exe) and the fake daemon (tools/fake_dragonxd)
+# for Windows with mingw-w64, then run the tests: directly under WSL (Windows interop), else with
+# wine if installed, else just build.
+#
+#   scripts/test-windows.sh [--no-run] [--jobs N]
+#
+# Uses its own build/windows-tests tree (full-node config), so build/windows is left alone. Needs
+# the mingw toolchain file that ./build.sh --win-release writes to build/windows/. Dependency sources
+# already fetched into build/windows/_deps are reused, so nothing is downloaded twice.
+set -euo pipefail
+
+repo="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+bd="$repo/build/windows-tests"
+toolchain="$repo/build/windows/mingw-toolchain.cmake"
+deps="$repo/build/windows/_deps"
+run=true
+jobs=8   # each test TU is large; several parallel mingw builds can exhaust RAM
+
+while [[ $# -gt 0 ]]; do
+    case "$1" in
+        --no-run) run=false; shift ;;
+        --jobs)   jobs="$2"; shift 2 ;;
+        -h|--help) sed -n '2,10p' "$0" | sed 's/^# \{0,1\}//'; exit 0 ;;
+        *) echo "unknown option: $1" >&2; exit 2 ;;
+    esac
+done
+
+if [[ ! -f "$toolchain" ]]; then
+    echo "missing $toolchain; run ./build.sh --win-release once to create the mingw toolchain" >&2
+    exit 1
+fi
+
+src_args=()
+for dep in sdl3 json tomlplusplus sqlite3 curl libwebp; do
+    if [[ -d "$deps/$dep-src" ]]; then
+        src_args+=("-DFETCHCONTENT_SOURCE_DIR_${dep^^}=$deps/$dep-src")
+    fi
+done
+
+cmake -S "$repo" -B "$bd" \
+    -DCMAKE_TOOLCHAIN_FILE="$toolchain" \
+    -DCMAKE_BUILD_TYPE=Release \
+    -DDRAGONX_USE_SYSTEM_SDL3=OFF \
+    -DDRAGONX_BUILD_LITE=OFF \
+    -DDRAGONX_ENABLE_LITE_BACKEND=OFF \
+    -DBUILD_TESTING=ON \
+    -DDRAGONX_BUILD_FAKE_DAEMON=ON \
+    "${src_args[@]}"
+cmake --build "$bd" --target ObsidianDragonTests fake_dragonxd -j "$jobs"
+
+exe="$bd/bin/ObsidianDragonTests.exe"
+echo "built: $exe"
+echo "built: $bd/fake_dragonxd/dragonxd.exe"
+$run || exit 0
+
+# The fixture path compiled into the binary is a Linux path; hand the Windows process its own.
+# APPDATA/LOCALAPPDATA point at a sandbox so anything resolving them from the environment stays out
+# of the real profile. (SHGetFolderPath-based paths ignore the environment; the tests that would
+# write through those are compiled out on Windows.)
+export DRAGONX_TEST_FIXTURE_DIR="$repo/tests/fixtures"
+sandbox="$bd/test-appdata"
+mkdir -p "$sandbox"
+export APPDATA="$sandbox" LOCALAPPDATA="$sandbox"
+if grep -qi microsoft /proc/version 2>/dev/null && [[ -e /proc/sys/fs/binfmt_misc/WSLInterop ]]; then
+    # /p: translate each to a Windows path for the Windows process
+    export WSLENV="${WSLENV:+$WSLENV:}DRAGONX_TEST_FIXTURE_DIR/p:APPDATA/p:LOCALAPPDATA/p"
+    cd "$bd/bin"
+    exec "$exe"
+elif command -v wine >/dev/null 2>&1; then
+    export DRAGONX_TEST_FIXTURE_DIR="$(winepath -w "$DRAGONX_TEST_FIXTURE_DIR")"
+    cd "$bd/bin"
+    exec wine "$exe"
+else
+    echo "not on WSL and no wine: copy $exe (and tests/fixtures) to Windows to run it" >&2
+fi