Optionally Text-to-speech output of Siri Shortcuts commands

This allows for getting auditory feedback on the success of the command (also take a look at #625), and it also allows querying practically anything with Siri.

Start by reading the existing Siri Shortcuts command handling and the related issue #625. Trace how command success is reported, then determine the project’s existing text-to-speech integration points; done means successful commands can provide auditory feedback and Siri can query the supported command results.

Written by the indexing model from the issue text.