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/classroom_commands/chat.rs

@@ -47,6 +47,7 @@ pub struct ClassroomChatCmdRequest {
 // ---------------------------------------------------------------------------
 
 /// Send a message in the classroom chat and get multi-agent responses.
+// @connected
 #[tauri::command]
 pub async fn classroom_chat(
     store: State<'_, ClassroomStore>,
@@ -107,6 +108,7 @@ pub async fn classroom_chat(
 }
 
 /// Retrieve chat history for a classroom
+// @connected
 #[tauri::command]
 pub async fn classroom_chat_history(
     chat_store: State<'_, ChatStore>,