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/heartbeat.rs

@@ -708,6 +708,7 @@ pub type HeartbeatEngineState = Arc<Mutex<HashMap<String, HeartbeatEngine>>>;
 ///
 /// Restores persisted interaction time from VikingStorage so idle-greeting
 /// check works correctly across app restarts.
+// @connected
 #[tauri::command]
 pub async fn heartbeat_init(
     agent_id: String,
@@ -756,6 +757,7 @@ async fn restore_last_interaction(agent_id: &str) {
 }
 
 /// Start heartbeat engine for an agent
+// @connected
 #[tauri::command]
 pub async fn heartbeat_start(
     agent_id: String,
@@ -770,6 +772,7 @@ pub async fn heartbeat_start(
 }
 
 /// Stop heartbeat engine for an agent
+// @connected
 #[tauri::command]
 pub async fn heartbeat_stop(
     agent_id: String,
@@ -784,6 +787,7 @@ pub async fn heartbeat_stop(
 }
 
 /// Execute a single heartbeat tick
+// @connected
 #[tauri::command]
 pub async fn heartbeat_tick(
     agent_id: String,
@@ -797,6 +801,7 @@ pub async fn heartbeat_tick(
 }
 
 /// Get heartbeat configuration
+// @connected
 #[tauri::command]
 pub async fn heartbeat_get_config(
     agent_id: String,
@@ -810,6 +815,7 @@ pub async fn heartbeat_get_config(
 }
 
 /// Update heartbeat configuration
+// @connected
 #[tauri::command]
 pub async fn heartbeat_update_config(
     agent_id: String,
@@ -825,6 +831,7 @@ pub async fn heartbeat_update_config(
 }
 
 /// Get heartbeat history
+// @connected
 #[tauri::command]
 pub async fn heartbeat_get_history(
     agent_id: String,
@@ -840,6 +847,7 @@ pub async fn heartbeat_get_history(
 
 /// Update memory stats cache for heartbeat checks
 /// This should be called by the frontend after fetching memory stats
+// @connected
 #[tauri::command]
 pub async fn heartbeat_update_memory_stats(
     agent_id: String,
@@ -852,6 +860,7 @@ pub async fn heartbeat_update_memory_stats(
 }
 
 /// Record a user correction for personality improvement detection
+// @connected
 #[tauri::command]
 pub async fn heartbeat_record_correction(
     agent_id: String,
@@ -863,6 +872,7 @@ pub async fn heartbeat_record_correction(
 
 /// Record a user interaction for idle greeting detection
 /// Call this from frontend whenever user sends a message
+// @connected
 #[tauri::command]
 pub async fn heartbeat_record_interaction(
     agent_id: String,