Updated getPortableDataPath to prefer storing 'user-data' in Documents/My Games/<AppName>, with a fallback to the app directory if necessary. This enhances data portability and aligns with common user data storage conventions.
Portable mode now works on Windows, macOS, and Linux, storing user data in a 'user-data' folder within the app directory by default. The mode is enabled by default and can be disabled via NEBULA_PORTABLE=0. All file operations for history and search data now respect portable mode, using secure file writes where appropriate. Updated .gitignore and package.json to exclude portable data from versioning and packaging. Also fixed Bing icon filename case in home.html.
andrew