chore(scripts): document and guard mingw-w64 setup

- check_all.sh: guard Windows cross-compile step with command -v check
  instead of failing unconditionally; print install hint when skipped
- project_init.sh: add Linux/WSL setup path alongside existing macOS
  path — installs build-essential/cmake/glfw/wgpu-native via apt-get,
  prints mingw-w64 install hint if cross-compile toolchain is absent

2 files changed, 42 insertions, 4 deletions

diff --git a/scripts/check_all.sh b/scripts/check_all.sh
index 1a8b406..c2f749c 100755
--- a/scripts/check_all.sh
+++ b/scripts/check_all.sh
@@ -48,7 +48,11 @@ echo "Running coverage test suite..."
 
 echo ""
 echo "--- Running Windows Cross-Compilation Build ---"
-./scripts/build_win.sh
+if command -v x86_64-w64-mingw32-gcc >/dev/null 2>&1; then
+  ./scripts/build_win.sh
+else
+  echo "Skipped: mingw-w64 not found. Install with: sudo apt-get install -y mingw-w64"
+fi
 
 echo ""
 echo "All checks passed successfully."
diff --git a/scripts/project_init.sh b/scripts/project_init.sh
index 4ee1c13..953e5e5 100755
--- a/scripts/project_init.sh
+++ b/scripts/project_init.sh
@@ -32,18 +32,52 @@ else
   echo "glfw3webgpu already present."
 fi
 
-# Check for brew dependencies (macOS)
+# Platform-specific system dependencies
 if command -v brew >/dev/null 2>&1; then
+  # macOS
   for pkg in wgpu-native glfw; do
     if ! brew list "$pkg" >/dev/null 2>&1; then
-      echo "Warning: $pkg not found via brew. Installing..."
+      echo "Installing $pkg via brew..."
       brew install "$pkg"
     else
       echo "$pkg found (via brew)."
     fi
   done
+elif command -v apt-get >/dev/null 2>&1; then
+  # Linux / WSL
+  echo "Installing Linux build dependencies..."
+  sudo apt-get update -qq
+  sudo apt-get install -y \
+    build-essential cmake git python3 \
+    libglfw3-dev libxinerama-dev libxcursor-dev libxi-dev libxrandr-dev
+
+  if [ ! -f /usr/local/lib/libwgpu_native.so ]; then
+    echo "wgpu-native not found. Fetching prebuilt release..."
+    WGPU_VER="v0.19.4.1"
+    curl -L -o /tmp/wgpu_linux.zip \
+      "https://github.com/gfx-rs/wgpu-native/releases/download/${WGPU_VER}/wgpu-linux-x86_64-release.zip"
+    mkdir -p /tmp/wgpu_tmp
+    unzip -q /tmp/wgpu_linux.zip -d /tmp/wgpu_tmp
+    sudo cp /tmp/wgpu_tmp/libwgpu_native.so /usr/local/lib/
+    sudo cp /tmp/wgpu_tmp/wgpu.h /tmp/wgpu_tmp/webgpu.h /usr/local/include/
+    sudo ldconfig
+    rm -rf /tmp/wgpu_linux.zip /tmp/wgpu_tmp
+    echo "wgpu-native installed."
+  else
+    echo "wgpu-native found."
+  fi
+
+  # Windows cross-compilation toolchain (optional)
+  if ! command -v x86_64-w64-mingw32-gcc >/dev/null 2>&1; then
+    echo ""
+    echo "Note: mingw-w64 not found (needed for Windows cross-compile)."
+    echo "  sudo apt-get install -y mingw-w64 && ./scripts/fetch_win_deps.sh"
+  else
+    echo "mingw-w64 found."
+  fi
 else
-  echo "Warning: Homebrew not found. Ensure wgpu-native and glfw are installed manually."
+  echo "Warning: Neither Homebrew nor apt-get found."
+  echo "See doc/HOWTO.md for manual installation instructions."
 fi
 
 echo "Done."