Implement business and customer profile list endpoints

[FriggemannMichael]

Objective:
Implement GET /api/profiles/business/ and GET /api/profiles/customer/.

Acceptance criteria:

• Business endpoint returns only business profiles.
• Customer endpoint returns only customer profiles.
• Endpoints require authentication.
• Response fields match frontend and endpoint documentation.
• Lists are usable by review and order templates in the frontend.

[FriggemannMichael]

TDD workflow for this project:

• Define the expected behavior before implementing the endpoint or model behavior.
• Write or outline the failing test first.
• Implement only enough code to make that test pass.
• Refactor after the test passes.
• Keep Django check, Ruff, and the relevant tests green from the local virtual environment.