UI - page where the client selects the businesses they want associated with their account

Note: some users will be using an existing account that already has affiliations, so if possible we should present those here as well

Design in review:
https://www.figma.com/design/AlpNJts0wCsWn6pDY1Zpti/Mass-Affiliation?node-id=1315-9341

Start with the linked Figma design and inspect the existing account affiliation flow in the Vue frontend. The page should let clients select businesses to associate with their account and, where available, show affiliations from an existing account; confirm the final behavior against the design.

Written by the indexing model from the issue text.