refactor: move guides from left toolbar to settings

- Remove guides from LeftToolbar pane type buttons
- Remove 'guides' from PaneType union and PANE_LABELS
- Remove GuidesPane from pane exports and ThreePanelLayout rendering
- Add migration to reset persisted slots that had type 'guides'
- Guides remain accessible via Settings modal (GuidesViewer tab)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/components/layout/LeftToolbar.tsx

@@ -7,7 +7,6 @@ import {
   LayoutList,
   Map,
   Folder,
-  FileText,
   Settings,
 } from 'lucide-react';
 import type { PaneType } from '../panes/types';
@@ -22,23 +21,21 @@ interface LeftToolbarProps {
   slotBType: PaneType | null;
 }
 
-// Map pane types to their icons (chat removed in rah-light)
+// Map pane types to their icons (chat removed in rah-light, guides moved to settings)
 const PANE_TYPE_ICONS: Record<string, typeof LayoutList> = {
   views: LayoutList,
   map: Map,
   dimensions: Folder,
-  guides: FileText,
 };
 
 const PANE_TYPE_LABELS: Record<string, string> = {
   views: 'Feed',
   map: 'Map',
   dimensions: 'Dimensions',
-  guides: 'Guides',
 };
 
-// Pane types shown in the toolbar (excludes 'node' which is opened via Feed, chat removed in rah-light)
-const TOOLBAR_PANE_TYPES: PaneType[] = ['views', 'map', 'dimensions', 'guides'];
+// Pane types shown in the toolbar (excludes 'node', 'chat', and 'guides' which is in settings)
+const TOOLBAR_PANE_TYPES: PaneType[] = ['views', 'map', 'dimensions'];
 
 interface ToolbarButtonProps {
   icon: typeof Search;