Refactor localization strings to use constant for text domain; add image context limit feature

- Updated localization strings in various classes to use the constant `GROQ_AI_PRODUCT_TEXT_DOMAIN` instead of hardcoded text domain.
- Introduced an image context limit setting in the settings manager and adjusted related methods to accommodate this new feature.
- Modified prompt builder to handle image context limit when building product context blocks and retrieving image payloads.
- Enhanced error handling and response structures to include new fields related to image context.
- Added support for title suggestions in the structured response from the AI.

includes/Providers/class-groq-ai-provider-openai.php

@@ -6,7 +6,7 @@ class Groq_AI_Provider_OpenAI extends Groq_AI_Abstract_OpenAI_Provider {
 	}
 
 	public function get_label() {
-		return __( 'OpenAI', 'groq-ai-product-text' );
+		return __( 'OpenAI', GROQ_AI_PRODUCT_TEXT_DOMAIN );
 	}
 
 	public function get_default_model() {