fix: Windows support & cross-platform architecture

Major fixes for Windows portable version:

1. **Fixed critical bugs:**
   - Replace Unix /dev/null with Windows nul in all .bat files
   - Unified config path to data/.openclaw/openclaw.json
   - Fixed cross-platform node_modules compatibility issue

2. **Implemented separated core directories:**
   - app/core-mac/ for Mac dependencies
   - app/core-win/ for Windows dependencies
   - Prevents cross-platform file system conflicts
   - Shared data/ directory for configs and memory

3. **Enhanced setup.sh:**
   - Now downloads both Mac and Windows Node.js runtimes
   - Ensures U-Claw works on both platforms after setup

4. **Added diagnostic tools:**
   - Windows-Diagnose.bat for troubleshooting
   - Mac-Diagnose.command for troubleshooting
   - Auto-generates diagnostic-log.txt

5. **Improved user experience:**
   - Added Welcome.html - Simple 3-step guide in Chinese
   - All scripts updated to use platform-specific core directories
   - Better error messages and user guidance

Files modified:
- portable/Windows-Start.bat: Use core-win, fix syntax
- portable/Windows-Menu.bat: Use core-win, fix syntax
- portable/Mac-Start.command: Use core-mac
- portable/Mac-Menu.command: Use core-mac
- portable/setup.sh: Download both platforms, use core-mac

Files added:
- portable/Windows-Diagnose.bat: Diagnostic tool
- portable/Mac-Diagnose.command: Diagnostic tool
- portable/Welcome.html: User-friendly welcome page

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

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

portable/Mac-Menu.command

@@ -4,7 +4,7 @@
 
 UCLAW_DIR="$(cd "$(dirname "$0")" && pwd)"
 APP_DIR="$UCLAW_DIR/app"
-CORE_DIR="$APP_DIR/core"
+CORE_DIR="$APP_DIR/core-mac"
 DATA_DIR="$UCLAW_DIR/data"
 STATE_DIR="$DATA_DIR/.openclaw"
 CONFIG_PATH="$STATE_DIR/openclaw.json"