feat: workspace panel visual overhaul, perf optimizations, remove kernel base addresses

Workspace panel:
- Custom WorkspaceDelegate: struct names bright, metadata dimmed, child types in teal
- Search box: monospace font, search icon, bordered with focus highlight
- Selection: accent bar, all fonts synced to 10pt monospace
- Remove rebuildWorkspaceModel from visibilityChanged (fixes double-click refresh)
- Incremental sync (syncProjectExplorer) preserves tree expansion state

Performance:
- childrenOf() O(1) via cached parent→children hash map
- Debounced workspace rebuilds (50ms coalesce)
- Pre-reserve node vector in NodeTree::fromJson
- Benchmark suite (bench_project)

Data:
- Remove kernel baseAddress from Vergilius/WinSDK examples (default to 0x400000)

src/mainwindow.h

@@ -24,6 +24,7 @@ namespace rcx {
 class McpBridge;
 class ShimmerLabel;
 class DockGripWidget;
+class WorkspaceDelegate;
 
 class MainWindow : public QMainWindow {
     Q_OBJECT
@@ -155,11 +156,14 @@ private:
     QStandardItemModel*   m_workspaceModel  = nullptr;
     QSortFilterProxyModel* m_workspaceProxy = nullptr;
     QLineEdit*            m_workspaceSearch = nullptr;
+    WorkspaceDelegate*    m_workspaceDelegate = nullptr;
     QLabel*               m_dockTitleLabel  = nullptr;
     QToolButton*          m_dockCloseBtn    = nullptr;
     DockGripWidget*       m_dockGrip        = nullptr;
     void createWorkspaceDock();
-    void rebuildWorkspaceModel();
+    void rebuildWorkspaceModel();       // debounced — safe to call frequently
+    void rebuildWorkspaceModelNow();    // immediate rebuild
+    QTimer*               m_workspaceRebuildTimer = nullptr;
     void updateBorderColor(const QColor& color);
 
     // Scanner dock