MoreCast 2.0: Persistence & Actuals

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

If the start date is set before today, have the table populate actuals so the forecaster can see how weather is changing or not from a persistence forecast perspective.

Re: question of which previous forecast to use to compare? To keep it simple, my vote would be for only the previous day's 12z model. Eg actual weather data for Wednesday, March 08 would be compared to the 'noon' forecast for March 08 from the model initialized at 12z March 07.

Rationale: The previous day's 12z data would have been the most recently available / 'freshest' guidance available to the forecaster when the forecaster inputted/updated the numbers the day before (if we exclude the 18z and 06z runs, as discussed on a recent meeting)

**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

Start by locating the MoreCast persistence forecast table and the code that handles a start date before today. Trace how actual weather data and model runs are represented, then determine how the previous day's 12z forecast should be selected for comparison. Done means historical rows show actuals alongside the agreed persistence forecast comparison.

Written by the indexing model from the issue text.