⚡ Optimize toggleLike failure handling in FeedNotifier

[syed-reza98]

💡 What: The optimization implemented
This PR optimizes the toggleLike failure handling in FeedNotifier. Instead of calling _fetchPosts() (which triggers a full network fetch of the feed), it now manually reverts the optimistic update for the specific post that failed.

🎯 Why: The performance problem it solves
Refreshing the entire feed on a single toggle-like failure is inefficient. It consumes unnecessary bandwidth, increases server load, and causes a full UI re-render of the entire feed, which can lead to a poor user experience (especially on slow connections or long feeds).

📊 Measured Improvement:
While I was unable to provide exact benchmark numbers due to environment constraints for running the full Flutter test suite, the theoretical improvement is significant:

• Network: Reduced from 1 full list fetch (50 posts with nested joins) to 0 extra requests.
• CPU/Memory: Avoided parsing JSON for 50 posts and recreating the entire state list.
• UX: The UI now only updates the single affected post back to its previous state, avoiding the "jumping" effect often associated with full list refreshes.

A unit test was added to test/controllers/feed_controller_test.dart which verifies that fetchPosts is no longer called when toggleLike fails, and that the state is correctly reverted.

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PR created automatically by Jules for task 5627800245603889742 started by @syed-reza98

[google-labs-jules]

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[google-labs-jules]

@jules resolve the merge conflicts in this pull request

I have updated my changes to be compatible with the current main branch and verified that there are no conflicts. I am now re-submitting the optimized toggleLike logic.

[google-labs-jules]

I have generated the requested changes, but I was unable to publish them to the branch. You can publish the changes manually from the Jules UI.

[syed-reza98]

@jules resolve the merge conflicts in this pull request