sync: Major UI updates from private repo (Jan 16-24)

Features synced:
- UI Panels Refactor: flexible pane system with ChatPane, NodePane,
  DimensionsPane, WorkflowsPane, ViewsPane, MapPane
- Source Content Reader: content type detection + 4 formatters
  (transcript, book, markdown, raw)
- Source Content Search: Cmd+F search in Source Reader
- Feed Layout Overhaul: LeftToolbar, SplitHandle, CollapsedRail
- Map Panel: promoted to first-class pane
- Edge policy simplification: auto-inference + direction correction

New files:
- src/components/panes/* (pane system)
- src/components/layout/CollapsedRail.tsx
- src/components/layout/LeftToolbar.tsx
- src/components/layout/SplitHandle.tsx
- src/components/focus/source/* (Source Reader + formatters)
- src/components/views/ViewsOverlay.tsx

Updated:
- ThreePanelLayout.tsx (complete refactor)
- FocusPanel.tsx (Source tab integration)
- API routes (dimensions GET, edges auto-inference)
- Database services (nodes, edges, dimensions)

Dependencies added:
- react-markdown
- remark-gfm

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/components/nodes/FolderViewOverlay.tsx

@@ -41,11 +41,12 @@ interface FolderViewOverlayProps {
   onNodeOpen: (nodeId: number) => void;
   refreshToken: number;
   onDataChanged?: () => void;
+  onDimensionSelect?: (dimensionName: string | null) => void;
 }
 
 const PAGE_SIZE = 100;
 
-export default function FolderViewOverlay({ onClose, onNodeOpen, refreshToken, onDataChanged }: FolderViewOverlayProps) {
+export default function FolderViewOverlay({ onClose, onNodeOpen, refreshToken, onDataChanged, onDimensionSelect: _onDimensionSelect }: FolderViewOverlayProps) {
   const [view, setView] = useState<'dimensions' | 'nodes'>('dimensions');
   const [dimensions, setDimensions] = useState<DimensionSummary[]>([]);
   const [dimensionsLoading, setDimensionsLoading] = useState(true);