HFI Calculator: Collapse planning areas

**As a** *Plans/R/ZWCO* **I want** *to be able to collapse Planning Areas* **So That** *I can have a more streamlined view / focus on one Zone at a time*

**Additional Context**
- import ExpandCircleDownOutlinedIcon from '@mui/icons-material/ExpandCircleDownOutlined';
- I’m transforming/rotating the icon, this is the only one. We can change this... but this one is my fav

**Acceptance Criteria**
- [ ] Given I am using HFI, When I click a collapse icon, Then the weather stations are hidden - only the data in the Planning Area row is visible
- [ ] Given I am using HFI, I can collapse all Planning Areas to only see the summaries
- [ ] Given I am using HFI, I can expand all Planning Areas to see all weather station details

**Definition of Done**
- Ready to Demo in Sprint Review
- Does what I have made have appropriate test coverage?
- Documentation and/or scientific documentation exists and can be found
- Peer Reviewed by 2 people on the team
- Manual testing of all PRs in Dev and Prod
- Merged

Start by locating the HFI Calculator component that renders Planning Areas and weather station details, then inspect existing Material UI icon usage. Implement the collapse and expand-all behavior described in the acceptance criteria, with tests covering hidden station details and restored expanded views.

Written by the indexing model from the issue text.