Add context menu for vault actions and trash functionality

- Add UiButtonContext component for context menu support on buttons
- Implement vault trash functionality using trash crate
- Move vaults to system trash on desktop (with fallback to permanent delete on mobile)
- Add context menu to vault list items for better mobile UX
- Keep hover delete button for desktop users

src-tauri/src/lib.rs

@@ -68,6 +68,7 @@ pub fn run() {
         .invoke_handler(tauri::generate_handler![
             database::create_encrypted_database,
             database::delete_vault,
+            database::move_vault_to_trash,
             database::list_vaults,
             database::open_encrypted_database,
             database::sql_execute_with_crdt,