chore: remove unused test_settings() function from prompts.rs

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend/src/services/prompts.rs

@@ -179,29 +179,9 @@ pub fn build_article_classify_prompt(
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::models::settings::UserSettings;
     use chrono::Utc;
     use uuid::Uuid;
 
-    fn test_settings() -> UserSettings {
-        UserSettings {
-            user_id: Uuid::nil(),
-            max_articles_per_source: 3,
-            max_links_per_source: 8,
-            use_brave_search: false,
-            article_history_days: 90,
-            batch_size: 5,
-            source_extraction_window: 3,
-            search_agent_behavior: String::new(),
-            ai_provider: String::new(),
-            ai_model: String::new(),
-            ai_model_websearch: String::new(),
-            rate_limit_max_requests: None,
-            rate_limit_time_window_seconds: None,
-            updated_at: Utc::now(),
-        }
-    }
-
     // Test theme/categories for search prompt tests
     fn test_theme() -> String {
         "Intelligence Artificielle".to_string()