fix(tauri): replace silent let _ = with structured logging across 20 modules

Replace error-swallowing let _ = patterns with tracing::warn! in browser,
classroom, gateway, intelligence, memory, pipeline, secure_storage, and
viking command handlers. Ensures errors are observable in production logs.

desktop/src-tauri/src/memory/extractor.rs

@@ -473,6 +473,7 @@ If no significant memories found, return empty array: []"#,
 
 // === Tauri Commands ===
 
+// @connected
 #[tauri::command]
 pub async fn extract_session_memories(
     messages: Vec<ChatMessage>,
@@ -489,6 +490,7 @@ pub async fn extract_session_memories(
 
 /// Extract memories from session and store to SqliteStorage
 /// This combines extraction and storage in one command
+// @connected
 #[tauri::command]
 pub async fn extract_and_store_memories(
     messages: Vec<ChatMessage>,