[foursecondfivefour]

Summary

• Add opt-in parallel repacking with separate disjoint payload writes and verification before publication; extend benchmark and tests.
• Add a local path browser to the experimental GUI, guarded by the existing loopback, origin and session-token checks.
• Support UTF-16 command-line arguments on Windows, add Unicode-path tests and set up a Linux/Windows CI matrix with and without the GUI.

Checks

• CMake/Ninja build and eight CTest suites passed on Linux, including synthetic parallel-repack and GUI HTTP API tests.
• Synthetic benchmark run; results do not establish real-world performance.

Limitations

• GUI progress and cancellation are not implemented; repack output filenames must be entered manually.
• Windows CI has not yet run; interactive browser behavior and real game archives have not been validated.
• Python/C++ behavior has not been fully compared. Use private directories and keep backups.