Rename partner_logo to affiliate_logo and update core models/tests

[drakeredwind01]

Fixes #602

What changes did you make?

• Modified Affiliate model fields to match updated schema requirements.
• Updated AffiliateSerializer to include new/renamed fields.
• Refactored API endpoints to handle updated data structure.
• Updated unit tests to validate model changes and endpoint responses.
• Ran and applied new Django migrations for the Affiliate table.

Why did you make the changes (we will use this info to test)?

• Aligns the Affiliate table with the current VRMS data model.
• Ensures API consistency for frontend integration.-

[fyliu]

@drakeredwind01 You need to fill in the PR description.

• The issue number at the top links the PR to the issue.
• The changes portion I usually look at the code changes and say what they are
• The reasons should answer the question "what does the project gain from making this change?"
• You can skip the screenshots or attach what it looks like in the admin site, before and after. See this other PR description and do something like that.
• Also, you should havae assigned a reviewer. It sets me as the reviewer after I did a review. Once you're ready, be sure to click the "re-request view" icon next to the reviwer at the top right.

[drakeredwind01]

@fyliu i updated the template. thanks!

Fixed

[fyliu]

Looks good!