Configuration panel now has a 'Xilinx Kit:' row at the top with:
- Entry field showing current path
- [Browse] button using system directory dialog (cross-platform)
- Select root directory (e.g. /data/xilinx or C:/Xilinx)
vitis_checker.py now scans xilinx_root subdirectories:
1. System PATH (shutil.which) — works on all platforms
2. Legacy vitis_path/bin
3. xilinx_root/Vitis/*/bin and Vivado/*/bin (all versions, newest first)
4. Common install paths (Windows: C:/Xilinx, Linux: /data/xilinx, /opt/xilinx)
Multi-version: scans all version directories under Vitis/ and Vivado/,
picks the newest version for each tool.
Config: xilinx_path replaces vitis_path (backward compat kept)