Update Excel Export to Include Watershed Screenshot - WALLY

**As a** WALLY user **I want** a screenshot of the full extent of the watershed being assessed to be exported into the Excel **so that** I am able to further analyze EFN (Environmental Flow Needs) risk or make further adjustments as necessary.

**Acceptance Criteria**
- [ ] Given a WALLY user selects watershed data, when they export the data, then they are given a screenshot of the full extent of the watershed being assessed to be exported into the Excel
- [ ] Export should have this data in the Summary tab

Sample screenshot that user has to search for manually

**Additional Context**
- Data to be included in the Excel export that is not currently being exported and is manually added into Excel to evaluate EFN risk
- Export function: This function allows users to export to Excel (or as a shapefile). However, the current output from WALLY into Excel only contains partial information that is found in the online staging environment.
- Data is already in Wally
- This does not require any calculations

Start at WALLY's existing Excel export entry point and trace how watershed selections are written to the Summary tab. Run an export with watershed data and identify where the full-extent screenshot can be included; done means the exported workbook contains that screenshot in Summary without adding calculations.

Written by the indexing model from the issue text.