[mattmcbeardface]

Changes

• Fix the game's built-in updater by launching with the correct working directory.
• Support updated official Pokémon MSI installers without hardcoded checksums.
• Verify installer signatures, publisher identity, and certificate validation.
• Improve interrupted-download handling, cache safety, and concurrent installer acquisition.
• Update application version and release notes to 0.1.4.

Validation

• 58 automated tests passed.
• Existing game successfully updated and launched.
• Fresh Flatpak installation from a .flatpakref succeeded.
• First-launch installation and authentication verified.

Closes #1