Engine update + some bugfixing

- [Engine] Updated to Unity6
- [Inventory] Fixed buttons positioning, optimizations
- [Shop] Fixed: player facing wrong direction when giving battery or lenses to the Shopkeeper
- [Joypad Config Menu] fixed fonts, fixed positioning on 21:9 display
- [Engine] Fixed a bug that caused the keybindings to reset on game restart (only pc, mac, linux)
- [Splash Screen] Fixed a bug that caused the pause menu to be accessed while the BM logo is displayed
- [Conversation Menu] - fixed first element select on open when mouse input is enabled (only pc, mac, linux)
- [Engine] Improved AVR objects pixel rendering
- [Nuwaka / Internet Store] Fixed: player facing wrong direction when talking with Netrunner
- [Journal] Improved font rendering
- [Slums] Fixed: Pedestrian conversation already selected dialogue options not retaining the selected colour on scene reload
- [Slums] Fixed missing . in "Hi, I'm Nathan" dialogue line (English only)
- [Engine] Fixed: mouse cursor not retaining size on aspect ratios different than 16:9
- [Engine] Fixed: interaction menu not retaining size on aspect ratios different than 16:9
- [Engine] Fixed: Inventory grid occasionally allowing scrolling to an extra blank row
- [Underwater / Base Outside] Fixed fishes sprites priority glitch
- [Space / Museum] Fixed camera glitch when exiting the scene
- [Space / Tourist Point] Improved navigation mesh
- [Main Menu] Fixed: "Start Journey" highlight colour stays stuck when Joypad navigation is used
- [Club / Bar] Fixed a bug that prevented Nathan to reach the Pill Dispenser when examining it