Add option to show/hide hidden files in file explorer

[CatoMaior]

Summary

This PR adds a new toggle option "Show hidden files" to the file explorer menu (three-dot overflow menu). When disabled (default), files and directories starting with a dot (.) are filtered out from the view.

Motivation

When browsing remote Linux/Unix systems via SFTP, the file explorer displays all dotfiles (.bashrc, .config, .local, .cache, etc.) by default. These hidden configuration files clutter the view and make it harder to navigate to the actual content you're looking for. This feature provides a cleaner browsing experience while still allowing users to access hidden files when needed.

Changes

• Added "Show hidden files" toggle in the file explorer overflow menu
• Hidden files (names starting with .) are filtered by default
• Toggle state is persisted across app restarts via SharedPreferences
• Filter is applied consistently across all views: directory listing, search results, and sorting

Screenshots

Show hidden files: ON	Show hidden files: OFF