feat: implement comprehensive retry mechanism and improve observability

Add retry tracking to scrape jobs with configurable max retries (default 5), implement
automatic database migrations on startup, and significantly reduce logging noise from
infrastructure layers. Enhanced tracing with structured spans for better debugging while
keeping output readable by suppressing verbose trace logs from rate limiters and session
management. Improved error handling with detailed retry context and proper session cookie
validation.

src/app.rs

@@ -62,6 +62,14 @@ impl App {
             "database pool established"
         );
 
+        // Run database migrations
+        info!("Running database migrations...");
+        sqlx::migrate!("./migrations")
+            .run(&db_pool)
+            .await
+            .expect("Failed to run database migrations");
+        info!("Database migrations completed successfully");
+
         // Create BannerApi and AppState
         let banner_api = BannerApi::new_with_config(
             config.banner_base_url.clone(),