Revert "fix: prevent sidebar clearing when opening new query tab (#576)"

This reverts commit 905aff8.

Author: datlechin

TablePro/Models/Query/EditorTabPayload.swift

@@ -93,10 +93,8 @@ internal struct EditorTabPayload: Codable, Hashable {
     /// Whether this payload is a "connection-only" payload — just a connectionId
     /// with no specific tab content. Used by MainContentView to decide whether
     /// to create a default tab or restore tabs from storage.
-    /// Note: isNewTab payloads (from the "+" button) are NOT connection-only —
-    /// they are explicit requests to open a new query tab.
     internal var isConnectionOnly: Bool {
-        tabType == .query && tableName == nil && initialQuery == nil && !isNewTab
+        tabType == .query && tableName == nil && initialQuery == nil
     }
 
     /// Create a payload from a persisted QueryTab for restoration

TablePro/Views/Main/MainContentView.swift

@@ -450,13 +450,7 @@ struct MainContentView: View {
     private func initializeAndRestoreTabs() async {
         guard !hasInitialized else { return }
         hasInitialized = true
-
-        // Only load schema if this is the first window for this connection.
-        // Additional windows share the same driver — concurrent schema load
-        // races with health monitor pings and can crash single-connection drivers.
-        if !WindowLifecycleMonitor.shared.hasOtherWindows(for: connection.id, excluding: windowId) {
-            Task { await coordinator.loadSchemaIfNeeded() }
-        }
+        Task { await coordinator.loadSchemaIfNeeded() }
 
         // If payload provided a specific tab (not connection-only), execute its query immediately
         if let payload, !payload.isConnectionOnly {