Keep Salesforce next steps in line with the latest call

**Objective:** Update the next step on the Salesforce opportunity {opportunity-name} from what was agreed on its latest Chorus conversation.

**Step 1: Find the opportunity in Salesforce**

Call `salesforce-get-opportunity` with name = {opportunity-name}, falling back to name.contains. If more than one matches, list them and stop. If the opportunity is closed, say so and stop.

**Step 2: Find the latest conversation in Chorus**

Call `chorus-get-engagements` with account-name = the opportunity's account-name and date.from = today minus 90 days. Prefer conversations whose opportunity-name matches the Salesforce opportunity; otherwise use the account's conversations. Take the most recent one that has a meeting-summary.

**Step 3: Propose the change**

From that meeting-summary, write a next step of at most 255 characters: what happens next, who does it, and by when if the summary says. Show the current next step, the proposed one, and the conversation it came from (date and subject). If the summary suggests a different stage, mention it as a note but do not change it. Ask the user to confirm.

**Step 4: Write and confirm**

Only after the user says yes, call `salesforce-update-opportunity` with id = the opportunity-id and next-step = the approved text, and nothing else. Then call `salesforce-get-opportunity` with opportunity-id to show the stored value.

**Rules & Guidelines:**

* `salesforce-get-opportunity` and `salesforce-update-opportunity` are on the Salesforce server. `chorus-get-engagements` is on the Chorus server.
* `salesforce-update-opportunity` is the only tool that may write, once, and only the next-step field. Never pass stage, amount, probability or close-date.
* Do not call `salesforce-add-task` or any Chorus write tool.

**Validation:**

* If there is no conversation with a meeting-summary in the last 90 days, say so and stop without writing.
* If the summary names no clear next step, say so and ask the user to write one rather than inventing it.