MoreCast 2.0: Selecting Models for Specific Periods

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

Feature Request = It would be nice to have the capacity to chose different models for different time periods, for e.g. I want HRDPS temps for day 1-2, RDPS temps for 3 and GDPS for days 4-7.

**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

The issue names no files, tests, or entry points, and its acceptance criteria are still placeholders. First clarify the supported time ranges and expected behavior, then trace the existing forecast-model selection flow. Done means users can select HRDPS, RDPS, and GDPS for different forecast periods, with the agreed scenarios covered by tests.

Written by the indexing model from the issue text.