Implement /flood/stations Endpoint

[davidshin0302]

1. Task: Create an endpoint to return households in multiple fire stations’ jurisdictions.

2. Details:

3. Accepts a list of station numbers as a query parameter.

4. Groups people by household address and includes their name, phone, age, medications, and allergies.

5. Suggested Steps:

• Retrieve residents by station numbers.
• Group data by household addresses.
• Create a nested DTO structure for grouping residents under each address.