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/health_check.rs

@@ -112,6 +112,7 @@ fn get_process_uptime(status: &LocalGatewayStatus) -> Option<u64> {
 }
 
 /// Perform comprehensive health check on ZCLAW Kernel
+// @connected
 #[tauri::command]
 pub fn zclaw_health_check(
     app: AppHandle,
@@ -266,6 +267,7 @@ pub fn zclaw_health_check(
 }
 
 /// Quick ping to check if ZCLAW is alive (lightweight check)
+// @reserved: 暂无前端集成
 #[tauri::command]
 pub fn zclaw_ping(app: AppHandle) -> Result<bool, String> {
     let port_check = check_port_accessibility("127.0.0.1", ZCLAW_DEFAULT_PORT, 1000);