0.3.7 - Non-ASCII paths, front menu and install message fixes

Fixes non-ASCII file and folder names on Windows, the front menu hand-over, the SCALING label, and install error messages. All four fixes were contributed by @shinmagus.

• Non-ASCII names on Windows (#15): ROMs and user folders whose names have accented, Japanese or other non-ASCII characters now work. Such a ROM is found and verified, and installing into such a folder no longer fails with "cannot open ROM". The program now runs with UTF-8 as its process code page, which needs Windows 10 version 1903 or later. A follow-up commit embeds the same manifest in the MinGW build that is released here; the pull request on its own covered only MSVC builds.
• Front menu hand-over (#16): closing the front menu with Esc, the menu button or the pad's back button, and playing on from the game's own title screen, now counts as handing the game over, just as START GAME does. Esc then opens the pause menu, and BACK TO TITLE has a title to return to.
• SCALING label (#14): OPTIONS > SCALING shows the mode actually in use. FIT and INTEGER had been swapped.
• Install error messages (#17): a failed install names the file or folder that failed instead of blaming the chosen ROM, and no longer leaves a 3 MB .part copy behind.

Validation: all 20 CTest cases pass on the MinGW build, including the 36,000-frame interpreter/recompiled lockstep and golden-frame runs. The headless runner and tests were also built with MSVC to confirm the manifest merges there. With a system-only PATH, the packaged Windows build verified a ROM named ナックルズ.32x, installed into user folders named usuário and ゲーム (both fail on 0.3.6), opened the pause menu on the second Esc, and showed SCALING FIT. The Android APK has not been tested on a device for this release; its changes affect only the menu.

Windows x64 and Android arm64-v8a/x86_64 builds are included. Android uses version code 10 and the same signing certificate as 0.3.6 for in-place updates. As before, the APK is debug-signed with Release native code.

You must supply your own Knuckles' Chaotix (Japan, USA) ROM. No ROM image or game assets are included.