Pull Request resolves # .

• I read the [Generative AI policy](https://developer.joomla.org/generative-ai-policy.html) and my contribution is either not created with the help of AI or is compatible with the policy and GNU/GPL 2 or later.

Summary of Changes

This PR introduces a dynamic "Active User Only" toggle to the Smart Search (com_finder) filter configuration.

Currently, author filtering in Finder is strictly static. This addition allows administrators to create a generic, dynamic filter (e.g., "My Content" or "My Articles") that automatically adapts to the currently logged-in user.

How it works:
A new toggle is added to the "Search by Author" taxonomy section. When enabled (custom_author_filter === 1), the save method in the filter model intercepts the payload, clears any statically checked author IDs, and dynamically injects the taxonomy ID of the active user.

Testing Instructions

1. Log into the Joomla backend and ensure you have at least two different users who have authored articles (e.g., User A and User B).
2. Go to Components -> Smart Search -> Index and click Index to ensure all authors are mapped in the taxonomy.
3. Go to Components -> Smart Search -> Filters and click New.
4. Expand the Search by Author section.
5. You should see the new Active User Only toggle. Set it to Yes.
6. Save the filter (Name it "My Articles" for example).
7. Go to Menus and create a new Menu Item of type Smart Search -> Search.
8. In the menu item settings, assign the "My Articles" filter you just created.
9. Frontend Test: Log in to the frontend as User A and perform a search. Verify the results only show articles authored by User A.
10. Log out, log in as User B, and perform the same search. Verify the results only show articles authored by User B.

Actual result BEFORE applying this Pull Request

Author filtering in Smart Search was strictly static. Administrators had to manually select specific authors using checkboxes. It was impossible to create a single, reusable filter that dynamically restricted search results to the currently logged-in user's content.

Expected result AFTER applying this Pull Request

Administrators can utilize the "Active User Only" toggle to create dynamic author filters. The system intelligently intercepts the save state and assigns the active user's taxonomy ID, enabling personalized "My Content" search experiences from a single filter configuration.

Link to documentations

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• Documentation link for guide.joomla.org:
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• Pull Request link for manual.joomla.org:
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