Implement Product Flagging Feature

## Description:
We need to add a flagging feature to allow users to report problematic or inappropriate products. This feature will help maintain the quality of the product listings and provide feedback for moderation.

## Requirements:
- Add a "Flag" button next to each product in the search results and on the product details page.
- Implement functionality to allow users to flag products for reasons such as "Inappropriate Content," "Incorrect Information," or "Other."
- Provide a form or prompt for users to add additional details or comments about the flagging reason.
- Ensure that flagged products are reviewed by the moderation team.

## Acceptance Criteria:
- Each product has a "Flag" button.
- Clicking the "Flag" button opens a form or prompt to select a flagging reason and provide optional comments.
- The flagged product details are sent to the moderation team for review.
- Users receive confirmation that their flagging submission has been received.

Look for the product search results component and product details page in the frontend code. The flag button needs UI integration and an API call to a backend endpoint for submitting flags. Check existing API routes for product-related actions to understand the pattern. The acceptance criteria define the user flow and confirmation.

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