feat: Add Gemini AI integration for product title and description optimization

- Implemented Gemini API service for generating optimized product titles and descriptions based on Google Merchant Center guidelines.
- Added settings for Gemini API key and model selection in user settings.
- Enhanced product management views to support AI-generated suggestions for titles and descriptions.
- Enabled state saving for various data tables across campaign, terms, logs, and products views.
- Introduced AI prompt templates for generating product descriptions and categories.

templates/campaigns/main_view.php

@@ -559,6 +559,7 @@ $( function()
           type: 'POST',
           url: '/campaigns/get_campaign_history_data_table/campaign_id=' + campaign_id,
         },
+        stateSave: true,
         processing: true,
         serverSide: true,
         searching: false,