NetVendor v12.7: Cross-Platform Compatibility & Bug Fixes

🔧 Cross-Platform Fixes:

• Consistent pathlib.Path usage for Windows/Linux/Mac compatibility
• Explicit UTF-8 encoding on all file operations (prevents encoding issues on Windows)
• Atomic file writes for cache files (prevents corruption if process interrupted)
• Enhanced error handling with clear, actionable messages

🐛 Bug Fixes:

• Fixed None vendor handling in offline mode (now shows 'Unknown' correctly)
• Fixed TypeError when formatting None vendors in vendor summary, CSV exports, and visualizations
• All edge cases verified and working (special characters, empty files, whitespace-only files)

📚 Documentation:

• Added comprehensive cross-platform compatibility section
• Enhanced error handling documentation
• Updated runtime considerations with cross-platform notes
• Clarified Windows/Linux/macOS usage patterns

✅ Testing:

• All 9 comprehensive tests pass
• Edge cases verified (special characters, empty files, None vendors, whitespace-only files)
• Cross-platform compatibility confirmed for Linux Debian, Intel Mac, and Windows

🔒 Reliability:

• No infinite hangs: All network operations bounded by timeouts
• File corruption protection: Atomic writes prevent data loss
• Graceful error handling: Clear messages for all failure scenarios