MoreCast 2.0: Export Functionality in the absence of WF1 Integration

**Describe the task**
In the absence of the WF1 Integration/READ/WRITE API do we require a Forecast Export Functionality?

**Acceptance Criteria**
- [ ] Completed + Saved out Forecast created
- [ ] Exported as a CSV for data entry purposes
- [ ] third

**Additional context**
- Add any other context about the task here.
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The issue names no files, tests, or entry points to start from. Review the unresolved WF1 Integration/READ/WRITE API dependency and clarify the forecast export workflow, CSV contents, and the incomplete acceptance criteria before implementation; done should include a completed, saved forecast exported as a usable CSV.

Written by the indexing model from the issue text.