[Gin890]

The program stores user data (user setting JSON, bug reports, screenshots, ...) at a single fixed location: the current working directory on Windows/Linux, or the user application data folder on macOS. Each has a drawback: local storage is good when running multiple program installs for multiple Switches, while the user app folder survives program updates.

This PR adds UI in the Global Settings panel for the user to control this.

UI (Global Settings panel, new "Data Storage" section at the top)

• User Data & Bug Reports Location — where the user setting JSON file and bug (error) reports are saved.
• Screenshots Location — where screenshots are saved.

Each is a dropdown with two options: User app (the OS user application data folder, e.g. %APPDATA%/<name> on Windows, ~/Library/Application Support/<name> on macOS, ~/.local/share/<name> on Linux) and Local (the folder the program runs from; on macOS, the folder that hosts the app).

Default behavior

When these new settings are not in the setting JSON file yet, the program keeps the current platform behavior: local on Windows and Linux, user app folder on macOS. (Linux previously had no user-app-path behavior; it now defaults to local, same as before.)

How it works

• GlobalAutoPaths gains a UserDataStorageLocation enum plus per-category location state. SETTINGS_PATH(), PROGRAM_SETTING_JSON_PATH(), ERROR_PATH(), and the error-report folders now follow the "user data" location; SCREENSHOTS_PATH() follows the "screenshots" location. All other paths (debug dumps, user files, log file, downloaded resources, ML data) keep the platform-default base.
• At startup, DETECT_SETTINGS_STORAGE_LOCATION() (called in Main.cpp before the settings are read) checks both candidate setting JSON files and reads from the one that exists; if both exist it uses the most recently modified one, and if neither exists it uses the platform default. This way a choice made in a previous session is honored when reading the settings.
• The two new options are persisted in the setting JSON under USER_DATA_STORAGE / SCREENSHOTS_STORAGE and keep the GlobalAutoPaths state in sync (on load and on change); switching location while running creates the folders at the new location so data can be saved there immediately.

Misc

• Error reports now use absolute paths for the unsent/sent folders (previously CWD-relative, which did not resolve to the user app folder on macOS).
• PersistentSettings::write() creates the setting folder if it is missing.

Testing

• The full Qt project does not build in this sandbox, so this is a draft for review.
• The new GlobalAutoPaths storage-location/detection logic was exercised with a standalone harness built from the real GlobalAutoPaths.cpp + Common/Cpp/Filesystem sources (all cases passed: neither file present, one file present, both present with different mtimes, runtime location switch).
• The JSON round-trip of the new EnumDropdownOption<UserDataStorageLocation> values (default, slug load, to_json, unknown slug ignored) was verified against the real options framework.

Please review the per-OS path choices (Filesystem_Windows.h / Filesystem_Mac.h / Filesystem_Linux.h) in particular.