feat: add terminal broadcast, context menu, and shell close

Complete multi-pane broadcast, standard terminal right-click actions, batch host selection with progress, and native ssh_close_shell so closing a pane tears down the remote shell.

Co-authored-by: Cursor <cursoragent@cursor.com>

src-tauri/src/commands/ssh.rs

@@ -121,6 +121,11 @@ pub fn ssh_shell_resize(
     operation(state.ssh.shell_resize(&shell_id, cols, rows))
 }
 
+#[tauri::command]
+pub fn ssh_close_shell(state: State<'_, AppState>, shell_id: String) -> OperationResponse {
+    operation(state.ssh.close_shell(&shell_id))
+}
+
 #[tauri::command]
 pub fn sftp_connect(state: State<'_, AppState>, connection_id: String) -> IdResponse {
     match state.ssh.create_sftp(&connection_id) {