Plot station's HFI on graph

**As a** *ZWCO* **I want** *to view the hourly HFI data for 1+ selected stations* **So That** *I can see how the HFI value changes throughout the day(s) based on model predictions*

**Additional Context**
- use model data for hourly values (or 3-hour values) and calculate FFMC, ISI, BUI (daily) and subsequently HFI - we will have to calculate these values from model data ourselves
- enter text here

**Acceptance Criteria**
- [ ] Given I am on the graph tab of HFI Calc, When I select a planning area from a dropdown, Then the hourly/3-hourly HFI of the stations within the planning area are displayed on the graph
- [ ] Given (Context), When (action carried out), Then (expected outcome)

No files, tests, or entry points are named. Start by locating the HFI Calc graph tab, the planning-area station selection, and the model-data sources; determine how hourly or three-hourly values and the required fire indices are produced. Done means selecting a planning area displays the stations' HFI values over time on the graph.

Written by the indexing model from the issue text.