FE 2.0 - Implement API integration for account management and account information UI

[notjackl3]

Add backend connectivity and API integration to both the account management (manage staff) and account information pages.

Notes:

• Use the existing UIs created in Tickets 1 and 2
• Use [TBD] for form state management
• Ensure proper error handling for network and validation errors
• Ensure proper loading states while data is being fetched or submitted
• Include a description of the ticket and the implementation in the PR (with screenshots showing loading, success, and error states for both pages!)

The goal is to:

• Fetch the current account info and list of staff members from the API on page load via GET request and populate the table
• Fetch available member type options from the API via GET request
• On "Save" in edit mode, send updated account info/member types to the API via PUT request
• Connect "+ New User" creation flow to the API via POST request
• Connect user deletion to the API via DELETE request
• Handle empty state (no staff members found)
• Display appropriate success/error messages for all operations