feat: enforce master token authentication and reasoning support

- Added strict token validation against LLM_PROXY__SERVER__AUTH_TOKENS.
- Integrated 'reasoning_content' support into providers and server responses.
- Updated AppState to carry valid auth tokens for request-time validation.

src/lib.rs

@@ -69,13 +69,17 @@ pub mod test_utils {
             providers: std::collections::HashMap::new(),
         };
         
+        let (dashboard_tx, _) = tokio::sync::broadcast::channel(100);
+        
         Arc::new(AppState {
             provider_manager,
             db_pool: pool.clone(),
             rate_limit_manager: Arc::new(rate_limit_manager),
             client_manager,
-            request_logger: Arc::new(crate::logging::RequestLogger::new(pool.clone())),
+            request_logger: Arc::new(crate::logging::RequestLogger::new(pool.clone(), dashboard_tx.clone())),
             model_registry: Arc::new(model_registry),
+            dashboard_tx,
+            auth_tokens: vec![],
         })
     }