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/intelligence/compactor.rs

@@ -506,18 +506,21 @@ impl ContextCompactor {
 // === Tauri Commands ===
 
 /// Estimate tokens for text
+// @connected
 #[tauri::command]
 pub fn compactor_estimate_tokens(text: String) -> usize {
     estimate_tokens(&text)
 }
 
 /// Estimate tokens for messages
+// @connected
 #[tauri::command]
 pub fn compactor_estimate_messages_tokens(messages: Vec<CompactableMessage>) -> usize {
     estimate_messages_tokens(&messages)
 }
 
 /// Check if compaction is needed
+// @connected
 #[tauri::command]
 pub fn compactor_check_threshold(
     messages: Vec<CompactableMessage>,
@@ -528,6 +531,7 @@ pub fn compactor_check_threshold(
 }
 
 /// Execute compaction
+// @connected
 #[tauri::command]
 pub async fn compactor_compact(
     messages: Vec<CompactableMessage>,