Add reproducible build system for wxWidgets WASM port

- Add unified patch (wxwidgets-wasm.patch) for build validation
- Add scripts:
  - generate-wxwidgets-patches.sh: Extract patches from wxwidgets state
  - build-wxwidgets-wasm-clean.sh: Build from clean clone + patches
  - build-wxuniversal-wasm.sh: Build wxWidgets for WASM
- Add wxWidgets-wasm-reference submodule (ahilss/wxWidgets-wasm)
- Update .gitignore for wxwidgets-clean/ directory

Base commit: 5ff25322553c1870cf20a2e1ba6f20ed50d9fe9a

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

scripts/generate-wxwidgets-patches.sh

@@ -0,0 +1,163 @@
+#!/bin/bash
+# Generate a single unified patch from current wxwidgets state
+# This captures ALL modifications including submodule config.sub changes
+
+set -e
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+PROJECT_ROOT="$(dirname "$SCRIPT_DIR")"
+WX_SOURCE="$PROJECT_ROOT/wxwidgets"
+PATCHES_DIR="$PROJECT_ROOT/patches/wxwidgets-wasm"
+PATCH_FILE="$PATCHES_DIR/wxwidgets-wasm.patch"
+
+echo "=== Generating wxWidgets WASM Unified Patch ==="
+echo "Source: $WX_SOURCE"
+echo "Output: $PATCH_FILE"
+
+# Verify wxwidgets exists (check for .git as file or directory - submodules use a file)
+if [ ! -e "$WX_SOURCE/.git" ]; then
+    echo "ERROR: wxwidgets is not a git repository"
+    exit 1
+fi
+
+# Create output directory
+mkdir -p "$PATCHES_DIR"
+
+cd "$WX_SOURCE"
+
+# Capture current commit SHA (the base we're patching from)
+CURRENT_COMMIT=$(git rev-parse HEAD)
+echo ""
+echo "Base commit: $CURRENT_COMMIT"
+
+# Start with empty patch file
+> "$PATCH_FILE"
+
+echo ""
+echo "=== Part 1: Main wxWidgets changes ==="
+# Mark all untracked files as "intent to add" (allows git diff to see them)
+git add -N .
+
+# Generate main diff (excluding submodule directory pointers, but including everything else)
+git diff HEAD -- . \
+    ':!3rdparty/catch' \
+    ':!3rdparty/nanosvg' \
+    ':!3rdparty/pcre' \
+    ':!src/expat' \
+    ':!src/jpeg' \
+    ':!src/png' \
+    ':!src/tiff' \
+    ':!src/zlib' \
+    >> "$PATCH_FILE"
+
+# Undo the intent-to-add
+git reset HEAD --quiet
+
+MAIN_LINES=$(wc -l < "$PATCH_FILE")
+echo "Added main changes ($MAIN_LINES lines so far)"
+
+echo ""
+echo "=== Part 2: Submodule config.sub changes ==="
+
+# Process each submodule config.sub
+add_submodule_config_sub() {
+    local submodule="$1"
+    local config_sub_path="$2"
+    local full_path="$WX_SOURCE/$config_sub_path"
+
+    if [ -d "$WX_SOURCE/$submodule" ] && [ -f "$full_path" ]; then
+        cd "$WX_SOURCE/$submodule"
+
+        # Get the relative path within the submodule
+        local rel_config_sub="${config_sub_path#$submodule/}"
+
+        # Check if config.sub is modified in this submodule
+        if ! git diff --quiet HEAD -- "$rel_config_sub" 2>/dev/null; then
+            echo "  Adding $config_sub_path"
+
+            # Generate diff with paths rewritten to be relative to main repo
+            git diff HEAD -- "$rel_config_sub" | sed "s|a/$rel_config_sub|a/$config_sub_path|g; s|b/$rel_config_sub|b/$config_sub_path|g" >> "$PATCH_FILE"
+        else
+            echo "  Skipping $config_sub_path (no changes)"
+        fi
+    else
+        echo "  Skipping $submodule (not found)"
+    fi
+}
+
+add_submodule_config_sub "3rdparty/pcre" "3rdparty/pcre/config.sub"
+add_submodule_config_sub "src/expat" "src/expat/expat/conftools/config.sub"
+add_submodule_config_sub "src/jpeg" "src/jpeg/config.sub"
+add_submodule_config_sub "src/png" "src/png/config.sub"
+add_submodule_config_sub "src/tiff" "src/tiff/config/config.sub"
+
+cd "$WX_SOURCE"
+
+TOTAL_LINES=$(wc -l < "$PATCH_FILE")
+echo ""
+echo "Total patch: $TOTAL_LINES lines"
+
+echo ""
+echo "=== Generating checksums ==="
+cd "$PATCHES_DIR"
+shasum -a 256 *.patch > checksums.sha256
+echo "Created checksums.sha256"
+
+echo ""
+echo "=== Generating README ==="
+cat > README.md << EOF
+# wxWidgets WASM Port Patch
+
+Single unified patch that transforms wxWidgets into a WASM-capable build.
+
+## Base Version
+
+- Repository: git@github.com:VV-EE/wxWidgets.git
+- Commit: $CURRENT_COMMIT
+- Generated: $(date -u +"%Y-%m-%d %H:%M:%S UTC")
+
+## Patch Contents
+
+This single patch includes:
+- Main wxWidgets modifications (config.sub, configure.in, headers, sources)
+- New WASM platform: src/wasm/, include/wx/wasm/
+- New build files: build/wasm/
+- WASM theme renderer: src/univ/themes/wasm.cpp
+- Submodule config.sub updates for emscripten/wasm32 support:
+  - 3rdparty/pcre/config.sub
+  - src/expat/expat/conftools/config.sub
+  - src/jpeg/config.sub
+  - src/png/config.sub
+  - src/tiff/config/config.sub
+
+## Apply Instructions
+
+\`\`\`bash
+# Clone wxWidgets fork at the base commit
+git clone git@github.com:VV-EE/wxWidgets.git wxwidgets-clean
+cd wxwidgets-clean
+git checkout $CURRENT_COMMIT
+git submodule update --init --recursive
+
+# Apply the unified patch
+patch -p1 < /path/to/patches/wxwidgets-wasm/wxwidgets-wasm.patch
+
+# Build
+mkdir build && cd build
+emconfigure ../configure --host=emscripten --enable-universal ...
+emmake make
+\`\`\`
+
+## Verification
+
+\`\`\`bash
+shasum -a 256 -c checksums.sha256
+\`\`\`
+EOF
+echo "Created README.md"
+
+echo ""
+echo "=== Summary ==="
+ls -lh "$PATCHES_DIR"
+echo ""
+echo "Unified patch generated successfully!"