MoreCast 2.0: No Model Data/Using Previous Model Run

**As a** User Type/Persona
**I need** Feature/enhancement
**So That** Value, why is this needed, what does the user need to accomplish

When a model run is not available, we should be providing the previous model run by default and have a red flag that notifies forecasters that they are using the XXZ model run

**Acceptance Criteria**
- [ ] Given (Context), When (action carried out), Then (expected outcome)
- [ ] Given (Context), When (action carried out), Then (expected outcome)

**Additional Context**
- enter text here
- enter text here

**Definition of Done**
https://github.com/bcgov/wps/wiki/Definition-of-Done

No files, tests, or entry points are named. First clarify the model-run fallback behavior, the meaning of the XXZ run label, and where the forecaster warning should appear; done means the previous run is selected when current data is unavailable and the warning is visible and tested.

Written by the indexing model from the issue text.