feat(app): add queued message send-now controls

[edoedac0]

Summary

• add a queued-message control row in the app/desktop prompt input when users submit while a response is already in progress
• add Send now behavior that aborts the currently running response, removes the queued copy, and immediately sends that queued message
• add queue management actions for Remove from queue and Edit (restore queued prompt into input), and hide aborted error cards only for send-now-triggered aborts while keeping manual stop behavior unchanged

Linked Issue

Closes #12707
Related to #5333

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