Fix desktop notifications on GNOME 46+ Linux

[benthecarman]

Desktop notifications didn't work for me. Claude's vibe coded fix. This fixes the problem for me

The app posts every desktop notification through the Web Notification constructor, which tauri-plugin-notification routes to its notify command. That command calls notify-rust's show() and then drops the returned handle immediately. The handle owns the D-Bus connection used to post the notification, and on GNOME 46+ (Ubuntu 24.04, Fedora 41+) tearing that connection down dismisses the notification the instant it appears, so nothing is ever seen. macOS uses a different backend and is unaffected.

Add a Linux-only show_native_notification command that posts from a dedicated thread and holds the connection open via wait_for_action until the notification is closed. The same wait surfaces the default click action, which is forwarded to the frontend so clicking focuses the window and routes to the notification target. The web client now sends through this command on Linux and keeps the plugin path on macOS and Windows.

[wesbillman]

Blocking: desktop/src-tauri/Cargo.toml now declares the Linux target dependency table twice:

[target.'cfg(target_os = "linux")'.dependencies]

Cargo rejects duplicate TOML tables before it can compile, so the desktop crate fails immediately with:

error: duplicate key
  --> desktop/src-tauri/Cargo.toml:50:2

This is from adding the notify-rust Linux table above the existing Linux keyring table. Please merge notify-rust = "4" into the existing [target.'cfg(target_os = "linux")'.dependencies] block instead of creating a second one.

[benthecarman]

@wesbillman sorry, was not on latest master. Fixed!