feat(windows): add per-user/per-machine installation and multilingual support

[eduardomozart]

Description

This PR updates the Windows NSIS installer to allow users to choose between a per-user installation ("Just for me", which does not require UAC elevation) and a per-machine installation ("For anyone", which prompts for UAC elevation). Closes #540.

It leverages the NsisMultiUser plugin to properly handle registry views, uninstaller entries, and dynamic $INSTDIR switching. Additionally, it introduces auto-detected multilingual support for the installer interface, matching the translations already supported by the application.

Changes

• Added NsisMultiUser as a git submodule in ext/win-installer/NsisMultiUser.
• Refactored Installer.nsi to use MULTIUSER macros for initialization and uninstallation.
• Configured !define MULTIUSER_INSTALLMODE_64_BIT 1. Since the win64 gradle task bundles a 64-bit JRE and x86_64 SWT, this ensures the app correctly installs to Program Files instead of Program Files (x86) on per-machine installations.
• Updated .github/workflows/build.yml to include submodules: recursive in the checkout steps, ensuring the CI runner successfully fetches the NsisMultiUser dependency during the build process.
• Added 14 new MUI_LANGUAGE macros to the installer (matching the supported locales in Labels.LANGUAGES). The installer will now natively auto-detect the user's OS language and fallback to English when unsupported.

Dependencies & Notes

• Depends on Include swt-gdip-*.dll in Windows build #534 (related to issue Windows 3.10.0 crashes on startup: UnsatisfiedLinkError - swt-gdip-win32 missing (stripped from build) #532).
  Note: The installer itself compiles and works exactly as expected. However, when launching the application on Windows, it crashes on startup with an UnsatisfiedLinkError (swt-gdip-win32 missing). This PR requires Include swt-gdip-*.dll in Windows build #534 to be merged in order for the resulting Windows executable to run properly.