Enhance portable build and improve discovery process

[kbtale]

Portable and Robust Resource Path Handling

• Introduced a new runtime_paths.py module that provides resource_path and runtime_path helpers to correctly resolve resource and runtime file locations, supporting both development and frozen (portable) builds. All major modules now use these helpers for file access. [1] [2] [3] [4] [5] [6] [7] [8] [9]
• Updated documentation (README.md) to describe building a portable Windows executable and where resources are bundled and accessed at runtime.

Discovery and Scanning Improvements

• Added a fast, ARP-first ping sweep implementation in Python for Windows, used as a fallback for ping_sweep.ps1, improving scan speed and portability. This includes ARP table parsing, ICMP ping, and TCP connect fallback for host liveness detection. [1] [2] [3]
• Enhanced subnet filtering in discovery to exclude unsuitable networks (loopback, multicast, reserved, etc.) and limit scan scope for performance and accuracy. (F13df5d9L13R21, src/backend/discovery.pyL33-R38)
• Improved fallback logic in discovery: if no ICMP responders are found, the system now falls back to using default gateways as scan targets, ensuring mapping can proceed even in restricted environments. [1] [2] [3]

General Codebase Robustness

• All output files (reports, maps, inventories) are now written to the runtime directory using runtime_path, ensuring correct paths regardless of how the application is launched. [1] [2] [3]
• Improved logging and error handling in the main application flow to prevent crashes if the logging database is unavailable. [1] [2] [3]