Share the right part of a Chorus call, with an expiry

**Objective:** Create one shareable moment from the conversation `{conversation-subject}`, capturing `{what-to-capture}`, set to expire after `{expires-in-days}` days (default 30).

**Step 1: Resolve the conversation**

Call `chorus-get-engagements` with `subject.contains` set to `{conversation-subject}`. If more than one conversation matches, list subject, date, account and owner for each and stop, asking which one. If none match, widen the search once by using a shorter fragment of the subject, and stop if that finds nothing. Keep the `conversation-id`; it is the only value `chorus-add-moment` will accept as `call-id`.

**Step 2: Place the clip**

Read that conversation's `meeting-summary` and `duration`. Work out where in the recording `{what-to-capture}` occurs and choose a start offset in seconds and a length in seconds, between 30 and 120 seconds. If the summary does not let you place it, say so and ask for a timestamp rather than guessing.

**Step 3: Confirm before writing**

State the conversation subject and date, the start offset, the length, the subject line you will give the moment, the note, and the expiry date computed from `{expires-in-days}`. Ask for approval and stop.

**Step 4: Create the moment**

Only after approval, call `chorus-add-moment` exactly once, with `call-id` set to the conversation id, `moment-time` set to the start offset in seconds, `moment-duration` set to the length in seconds, `subject` set to the agreed title, `note` set to the agreed note, and `expiration-date` set to the computed date in ISO form. Do not call it a second time if the first call returns anything other than a clear failure, because a repeat call creates a duplicate moment.

**Step 5: Report**

Confirm what was created, against which conversation, and when it expires.

**Rules & Guidelines:**

* `chorus-add-moment` is the only write tool permitted, once. Do not call `chorus-add-playlist-moment`, `chorus-create-playlist`, `chorus-update-playlist`, `chorus-update-playlist-moment`, `chorus-update-moment`, `chorus-export-recordings` or `chorus-export-scorecards`.
* A shared moment is externally accessible. Always set an expiry date, and if the conversation involves an account, say which account in the confirmation so the sharer can judge the sensitivity.
* Offsets and durations are in seconds.

**Validation:**

* If the subject matches nothing, report that and stop.
* If the chosen offset plus the length exceeds the conversation `duration`, shorten the clip or move it back, and say that you did.